Hi,
Here is a batch of cleanups on the generic single IPI code. I've
gathered a few patches from Jan, split up some, and added a few more
so that __smp_call_function_single() becomes less obscure.
Comments?
git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
core/ipi-rfc
Thanks,
Frederic
---
Frederic Weisbecker (6):
block: Remove useless IPI struct initialization
smp: Consolidate the various smp_call_function_single() declensions
smp: Move __smp_call_function_single() below its safe version
watchdog: Simplify a little the IPI call
smp: Remove wait argument from __smp_call_function_single()
smp: Enhance and precise the role & requirements of __smp_call_function_single()
Jan Kara (5):
block: Stop abusing csd.list for fifo_time
block: Stop abusing rq->csd.list in blk-softirq
smp: Iterate functions through llist_for_each_entry_safe()
smp: Remove unused list_head from csd
smp: Teach __smp_call_function_single() to check for offline cpus
block/blk-mq.c | 2 +-
block/blk-softirq.c | 19 ++++---
block/cfq-iosched.c | 8 +--
block/deadline-iosched.c | 8 +--
drivers/block/null_blk.c | 2 +-
drivers/cpuidle/coupled.c | 2 +-
include/linux/blkdev.h | 1 +
include/linux/elevator.h | 11 +---
include/linux/smp.h | 8 +--
kernel/sched/core.c | 2 +-
kernel/smp.c | 139 ++++++++++++++++++++++------------------------
kernel/up.c | 4 +-
kernel/watchdog.c | 3 +-
net/core/dev.c | 2 +-
14 files changed, 97 insertions(+), 114 deletions(-)
rq_fifo_clear() reset the csd.list through INIT_LIST_HEAD for no clear
purpose. The csd.list doesn't need to be initialized as a list head
because it's only ever used as a list node.
Lets remove this useless initialization.
Cc: Andrew Morton <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
---
include/linux/elevator.h | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 0bdfd46..df63bd3 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -203,10 +203,7 @@ enum {
#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
-#define rq_fifo_clear(rq) do { \
- list_del_init(&(rq)->queuelist); \
- INIT_LIST_HEAD(&(rq)->csd.list); \
- } while (0)
+#define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
#else /* CONFIG_BLOCK */
--
1.8.3.1
From: Jan Kara <[email protected]>
The IPI function llist iteration is open coded. Lets simplify this
with using an llist iterator.
Also we want to keep the iteration safe against possible
csd.llist->next value reuse from the IPI handler. At least the block
subsystem used to do such things so lets stay careful and use
llist_for_each_entry_safe().
Signed-off-by: Jan Kara <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
---
kernel/smp.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
diff --git a/kernel/smp.c b/kernel/smp.c
index ffee35b..e3852de 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -151,7 +151,8 @@ static void generic_exec_single(int cpu, struct call_single_data *csd, int wait)
*/
void generic_smp_call_function_single_interrupt(void)
{
- struct llist_node *entry, *next;
+ struct llist_node *entry;
+ struct call_single_data *csd, *csd_next;
/*
* Shouldn't receive this interrupt on a cpu that is not yet online.
@@ -161,16 +162,9 @@ void generic_smp_call_function_single_interrupt(void)
entry = llist_del_all(&__get_cpu_var(call_single_queue));
entry = llist_reverse_order(entry);
- while (entry) {
- struct call_single_data *csd;
-
- next = entry->next;
-
- csd = llist_entry(entry, struct call_single_data, llist);
+ llist_for_each_entry_safe(csd, csd_next, entry, llist) {
csd->func(csd->info);
csd_unlock(csd);
-
- entry = next;
}
}
--
1.8.3.1
In order to remotely restart the watchdog hrtimer, update_timers()
allocates a csd on the stack and pass it to __smp_call_function_single().
There is no partcular need, however, for a specific csd here. Lets
simplify that a little by calling smp_call_function_single()
which can already take care of the csd allocation by itself.
Cc: Andrew Morton <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Don Zickus <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Srivatsa S. Bhat <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
---
kernel/watchdog.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 4431610..01c6f97 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -505,7 +505,6 @@ static void restart_watchdog_hrtimer(void *info)
static void update_timers(int cpu)
{
- struct call_single_data data = {.func = restart_watchdog_hrtimer};
/*
* Make sure that perf event counter will adopt to a new
* sampling period. Updating the sampling period directly would
@@ -515,7 +514,7 @@ static void update_timers(int cpu)
* might be late already so we have to restart the timer as well.
*/
watchdog_nmi_disable(cpu);
- __smp_call_function_single(cpu, &data, 1);
+ smp_call_function_single(cpu, restart_watchdog_hrtimer, NULL, 1);
watchdog_nmi_enable(cpu);
}
--
1.8.3.1
__smp_call_function_single() and smp_call_function_single() share some
code that can be factorized: execute inline when the target is local,
check if the target is online, lock the csd, call generic_exec_single().
Lets move the common parts to generic_exec_single().
Cc: Andrew Morton <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
---
kernel/smp.c | 80 +++++++++++++++++++++++++++++-------------------------------
1 file changed, 39 insertions(+), 41 deletions(-)
diff --git a/kernel/smp.c b/kernel/smp.c
index 5ff14e3..64bb0d4 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -117,13 +117,43 @@ static void csd_unlock(struct call_single_data *csd)
csd->flags &= ~CSD_FLAG_LOCK;
}
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
+
/*
* Insert a previously allocated call_single_data element
* for execution on the given CPU. data must already have
* ->func, ->info, and ->flags set.
*/
-static void generic_exec_single(int cpu, struct call_single_data *csd, int wait)
+static int generic_exec_single(int cpu, struct call_single_data *csd,
+ smp_call_func_t func, void *info, int wait)
{
+ struct call_single_data csd_stack = { .flags = 0 };
+ unsigned long flags;
+
+
+ if (cpu == smp_processor_id()) {
+ local_irq_save(flags);
+ func(info);
+ local_irq_restore(flags);
+ return 0;
+ }
+
+
+ if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu))
+ return -ENXIO;
+
+
+ if (!csd) {
+ csd = &csd_stack;
+ if (!wait)
+ csd = &__get_cpu_var(csd_data);
+ }
+
+ csd_lock(csd);
+
+ csd->func = func;
+ csd->info = info;
+
if (wait)
csd->flags |= CSD_FLAG_WAIT;
@@ -143,6 +173,8 @@ static void generic_exec_single(int cpu, struct call_single_data *csd, int wait)
if (wait)
csd_lock_wait(csd);
+
+ return 0;
}
/*
@@ -168,8 +200,6 @@ void generic_smp_call_function_single_interrupt(void)
}
}
-static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
-
/*
* smp_call_function_single - Run a function on a specific CPU
* @func: The function to run. This must be fast and non-blocking.
@@ -181,12 +211,8 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
int wait)
{
- struct call_single_data d = {
- .flags = 0,
- };
- unsigned long flags;
int this_cpu;
- int err = 0;
+ int err;
/*
* prevent preemption and reschedule on another processor,
@@ -203,26 +229,7 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
&& !oops_in_progress);
- if (cpu == this_cpu) {
- local_irq_save(flags);
- func(info);
- local_irq_restore(flags);
- } else {
- if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
- struct call_single_data *csd = &d;
-
- if (!wait)
- csd = &__get_cpu_var(csd_data);
-
- csd_lock(csd);
-
- csd->func = func;
- csd->info = info;
- generic_exec_single(cpu, csd, wait);
- } else {
- err = -ENXIO; /* CPU not online */
- }
- }
+ err = generic_exec_single(cpu, NULL, func, info, wait);
put_cpu();
@@ -285,9 +292,8 @@ EXPORT_SYMBOL_GPL(smp_call_function_any);
*/
int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
{
- unsigned int this_cpu;
- unsigned long flags;
int err = 0;
+ int this_cpu;
this_cpu = get_cpu();
/*
@@ -296,20 +302,12 @@ int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
* send smp call function interrupt to this cpu and as such deadlocks
* can't happen.
*/
- WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled()
+ WARN_ON_ONCE(cpu_online(this_cpu) && wait && irqs_disabled()
&& !oops_in_progress);
- if (cpu == this_cpu) {
- local_irq_save(flags);
- csd->func(csd->info);
- local_irq_restore(flags);
- } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
- csd_lock(csd);
- generic_exec_single(cpu, csd, wait);
- } else {
- err = -ENXIO; /* CPU not online */
- }
+ err = generic_exec_single(cpu, csd, csd->func, csd->info, wait);
put_cpu();
+
return err;
}
EXPORT_SYMBOL_GPL(__smp_call_function_single);
--
1.8.3.1
The main point of calling __smp_call_function_single() is to send
an IPI in a pure asynchronous way. By embedding a csd in an object,
a caller can send the IPI without waiting for a previous one to complete
as is required by smp_call_function_single() for example. As such,
sending this kind of IPI can be safe even when irqs are disabled.
This flexibility comes at the expense of the caller who then needs to
synchronize the csd lifecycle by himself and make sure that IPIs on a
single csd are serialized.
This is how __smp_call_function_single() works when wait = 0 and this
usecase is relevant.
Now there don't seem to be any usecase with wait = 1 that can't be
covered by smp_call_function_single() instead, which is safer. Lets look
at the two possible scenario:
1) The user calls __smp_call_function_single(wait = 1) on a csd embedded
in an object. It looks like a nice and convenient pattern at the first
sight because we can then retrieve the object from the IPI handler easily.
But actually it is a waste of memory space in the object since the csd
can be allocated from the stack by smp_call_function_single(wait = 1)
and the object can be passed an the IPI argument.
Besides that, embedding the csd in an object is more error prone
because the caller must take care of the serialization of the IPIs
for this csd.
2) The user calls __smp_call_function_single(wait = 1) on a csd that
is allocated on the stack. It's ok but smp_call_function_single()
can do it as well and it already takes care of the allocation on the
stack. Again it's more simple and less error prone.
Therefore, using the underscore prepend API version with wait = 1
is a bad pattern and a sign that the caller can do safer and more
simple.
There was a single user of that which has just been converted.
So lets remove this option to discourage further users.
Cc: Andrew Morton <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
---
block/blk-mq.c | 2 +-
block/blk-softirq.c | 2 +-
drivers/block/null_blk.c | 2 +-
drivers/cpuidle/coupled.c | 2 +-
include/linux/smp.h | 2 +-
kernel/sched/core.c | 2 +-
kernel/smp.c | 19 ++++---------------
kernel/up.c | 3 +--
net/core/dev.c | 2 +-
9 files changed, 12 insertions(+), 24 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 57039fc..87539d3 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -363,7 +363,7 @@ void blk_mq_end_io(struct request *rq, int error)
rq->csd.func = blk_mq_end_io_remote;
rq->csd.info = rq;
rq->csd.flags = 0;
- __smp_call_function_single(ctx->cpu, &rq->csd, 0);
+ __smp_call_function_single(ctx->cpu, &rq->csd);
} else {
__blk_mq_end_io(rq, error);
}
diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index b5c37d9..6345b7e 100644
--- a/block/blk-softirq.c
+++ b/block/blk-softirq.c
@@ -70,7 +70,7 @@ static int raise_blk_irq(int cpu, struct request *rq)
data->info = rq;
data->flags = 0;
- __smp_call_function_single(cpu, data, 0);
+ __smp_call_function_single(cpu, data);
return 0;
}
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 3107282..c6722dd 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -255,7 +255,7 @@ static void null_cmd_end_ipi(struct nullb_cmd *cmd)
if (llist_add(&cmd->ll_list, &cq->list)) {
data->func = null_ipi_cmd_end_io;
data->flags = 0;
- __smp_call_function_single(cpu, data, 0);
+ __smp_call_function_single(cpu, data);
}
put_cpu();
diff --git a/drivers/cpuidle/coupled.c b/drivers/cpuidle/coupled.c
index e952936..0411594 100644
--- a/drivers/cpuidle/coupled.c
+++ b/drivers/cpuidle/coupled.c
@@ -323,7 +323,7 @@ static void cpuidle_coupled_poke(int cpu)
struct call_single_data *csd = &per_cpu(cpuidle_coupled_poke_cb, cpu);
if (!cpumask_test_and_set_cpu(cpu, &cpuidle_coupled_poke_pending))
- __smp_call_function_single(cpu, csd, 0);
+ __smp_call_function_single(cpu, csd);
}
/**
diff --git a/include/linux/smp.h b/include/linux/smp.h
index 1e8c721..3664ef3 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -50,7 +50,7 @@ void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
smp_call_func_t func, void *info, bool wait,
gfp_t gfp_flags);
-int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait);
+int __smp_call_function_single(int cpu, struct call_single_data *csd);
#ifdef CONFIG_SMP
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b46131e..eba3d84 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -432,7 +432,7 @@ void hrtick_start(struct rq *rq, u64 delay)
if (rq == this_rq()) {
__hrtick_restart(rq);
} else if (!rq->hrtick_csd_pending) {
- __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
+ __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd);
rq->hrtick_csd_pending = 1;
}
}
diff --git a/kernel/smp.c b/kernel/smp.c
index fa04ab9..b767631 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -241,29 +241,18 @@ EXPORT_SYMBOL(smp_call_function_single);
* __smp_call_function_single(): Run a function on a specific CPU
* @cpu: The CPU to run on.
* @csd: Pre-allocated and setup data structure
- * @wait: If true, wait until function has completed on specified CPU.
*
* Like smp_call_function_single(), but allow caller to pass in a
* pre-allocated data structure. Useful for embedding @data inside
* other structures, for instance.
*/
-int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
+int __smp_call_function_single(int cpu, struct call_single_data *csd)
{
int err = 0;
- int this_cpu;
- this_cpu = get_cpu();
- /*
- * Can deadlock when called with interrupts disabled.
- * We allow cpu's that are not yet online though, as no one else can
- * send smp call function interrupt to this cpu and as such deadlocks
- * can't happen.
- */
- WARN_ON_ONCE(cpu_online(this_cpu) && wait && irqs_disabled()
- && !oops_in_progress);
-
- err = generic_exec_single(cpu, csd, csd->func, csd->info, wait);
- put_cpu();
+ preempt_disable();
+ err = generic_exec_single(cpu, csd, csd->func, csd->info, 0);
+ preempt_enable();
return err;
}
diff --git a/kernel/up.c b/kernel/up.c
index cdf03d1..4e199d4 100644
--- a/kernel/up.c
+++ b/kernel/up.c
@@ -22,8 +22,7 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
}
EXPORT_SYMBOL(smp_call_function_single);
-int __smp_call_function_single(int cpu, struct call_single_data *csd,
- int wait)
+int __smp_call_function_single(int cpu, struct call_single_data *csd)
{
unsigned long flags;
diff --git a/net/core/dev.c b/net/core/dev.c
index 3721db7..3f659b1 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4129,7 +4129,7 @@ static void net_rps_action_and_irq_enable(struct softnet_data *sd)
if (cpu_online(remsd->cpu))
__smp_call_function_single(remsd->cpu,
- &remsd->csd, 0);
+ &remsd->csd);
remsd = next;
}
} else
--
1.8.3.1
Be more specific on the description of __smp_call_function_single().
It's actually not that much about just being able to embed a csd
in an object.
Cc: Andrew Morton <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
---
kernel/smp.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/kernel/smp.c b/kernel/smp.c
index b767631..24cb936 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -238,13 +238,20 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
EXPORT_SYMBOL(smp_call_function_single);
/**
- * __smp_call_function_single(): Run a function on a specific CPU
+ * __smp_call_function_single(): Run an asynchronous function on a
+ * specific CPU.
* @cpu: The CPU to run on.
* @csd: Pre-allocated and setup data structure
*
- * Like smp_call_function_single(), but allow caller to pass in a
- * pre-allocated data structure. Useful for embedding @data inside
- * other structures, for instance.
+ * Like smp_call_function_single(), but the call is asynchonous and
+ * can thus be done from contexts with disabled interrupts.
+ *
+ * The caller passes his own pre-allocated data structure
+ * (ie: embedded in an object) and is responsible for synchronizing it
+ * such that the IPIs performed on the @csd are strictly serialized.
+ *
+ * NOTE: Be careful, there is unfortunately no current debugging facility to
+ * validate the correctness of this serialization.
*/
int __smp_call_function_single(int cpu, struct call_single_data *csd)
{
--
1.8.3.1
Move this function closer to __smp_call_function_single(). These functions
have very similar behavior and should be displayed in the same block
for clarity.
Cc: Andrew Morton <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
---
kernel/smp.c | 64 ++++++++++++++++++++++++++++++------------------------------
1 file changed, 32 insertions(+), 32 deletions(-)
diff --git a/kernel/smp.c b/kernel/smp.c
index 64bb0d4..fa04ab9 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -237,6 +237,38 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
}
EXPORT_SYMBOL(smp_call_function_single);
+/**
+ * __smp_call_function_single(): Run a function on a specific CPU
+ * @cpu: The CPU to run on.
+ * @csd: Pre-allocated and setup data structure
+ * @wait: If true, wait until function has completed on specified CPU.
+ *
+ * Like smp_call_function_single(), but allow caller to pass in a
+ * pre-allocated data structure. Useful for embedding @data inside
+ * other structures, for instance.
+ */
+int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
+{
+ int err = 0;
+ int this_cpu;
+
+ this_cpu = get_cpu();
+ /*
+ * Can deadlock when called with interrupts disabled.
+ * We allow cpu's that are not yet online though, as no one else can
+ * send smp call function interrupt to this cpu and as such deadlocks
+ * can't happen.
+ */
+ WARN_ON_ONCE(cpu_online(this_cpu) && wait && irqs_disabled()
+ && !oops_in_progress);
+
+ err = generic_exec_single(cpu, csd, csd->func, csd->info, wait);
+ put_cpu();
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(__smp_call_function_single);
+
/*
* smp_call_function_any - Run a function on any of the given cpus
* @mask: The mask of cpus it can run on.
@@ -281,38 +313,6 @@ call:
EXPORT_SYMBOL_GPL(smp_call_function_any);
/**
- * __smp_call_function_single(): Run a function on a specific CPU
- * @cpu: The CPU to run on.
- * @csd: Pre-allocated and setup data structure
- * @wait: If true, wait until function has completed on specified CPU.
- *
- * Like smp_call_function_single(), but allow caller to pass in a
- * pre-allocated data structure. Useful for embedding @data inside
- * other structures, for instance.
- */
-int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
-{
- int err = 0;
- int this_cpu;
-
- this_cpu = get_cpu();
- /*
- * Can deadlock when called with interrupts disabled.
- * We allow cpu's that are not yet online though, as no one else can
- * send smp call function interrupt to this cpu and as such deadlocks
- * can't happen.
- */
- WARN_ON_ONCE(cpu_online(this_cpu) && wait && irqs_disabled()
- && !oops_in_progress);
-
- err = generic_exec_single(cpu, csd, csd->func, csd->info, wait);
- put_cpu();
-
- return err;
-}
-EXPORT_SYMBOL_GPL(__smp_call_function_single);
-
-/**
* smp_call_function_many(): Run a function on a set of other CPUs.
* @mask: The set of cpus to run on (only runs on online subset).
* @func: The function to run. This must be fast and non-blocking.
--
1.8.3.1
From: Jan Kara <[email protected]>
Align __smp_call_function_single() with smp_call_function_single() so
that it also checks whether requested cpu is still online.
Signed-off-by: Jan Kara <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
---
include/linux/smp.h | 3 +--
kernel/smp.c | 11 +++++++----
kernel/up.c | 5 +++--
3 files changed, 11 insertions(+), 8 deletions(-)
diff --git a/include/linux/smp.h b/include/linux/smp.h
index 9a1b8ba..1e8c721 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -50,8 +50,7 @@ void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
smp_call_func_t func, void *info, bool wait,
gfp_t gfp_flags);
-void __smp_call_function_single(int cpuid, struct call_single_data *data,
- int wait);
+int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait);
#ifdef CONFIG_SMP
diff --git a/kernel/smp.c b/kernel/smp.c
index e3852de..5ff14e3 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -276,18 +276,18 @@ EXPORT_SYMBOL_GPL(smp_call_function_any);
/**
* __smp_call_function_single(): Run a function on a specific CPU
* @cpu: The CPU to run on.
- * @data: Pre-allocated and setup data structure
+ * @csd: Pre-allocated and setup data structure
* @wait: If true, wait until function has completed on specified CPU.
*
* Like smp_call_function_single(), but allow caller to pass in a
* pre-allocated data structure. Useful for embedding @data inside
* other structures, for instance.
*/
-void __smp_call_function_single(int cpu, struct call_single_data *csd,
- int wait)
+int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
{
unsigned int this_cpu;
unsigned long flags;
+ int err = 0;
this_cpu = get_cpu();
/*
@@ -303,11 +303,14 @@ void __smp_call_function_single(int cpu, struct call_single_data *csd,
local_irq_save(flags);
csd->func(csd->info);
local_irq_restore(flags);
- } else {
+ } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
csd_lock(csd);
generic_exec_single(cpu, csd, wait);
+ } else {
+ err = -ENXIO; /* CPU not online */
}
put_cpu();
+ return err;
}
EXPORT_SYMBOL_GPL(__smp_call_function_single);
diff --git a/kernel/up.c b/kernel/up.c
index 509403e..cdf03d1 100644
--- a/kernel/up.c
+++ b/kernel/up.c
@@ -22,14 +22,15 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
}
EXPORT_SYMBOL(smp_call_function_single);
-void __smp_call_function_single(int cpu, struct call_single_data *csd,
- int wait)
+int __smp_call_function_single(int cpu, struct call_single_data *csd,
+ int wait)
{
unsigned long flags;
local_irq_save(flags);
csd->func(csd->info);
local_irq_restore(flags);
+ return 0;
}
EXPORT_SYMBOL(__smp_call_function_single);
--
1.8.3.1
From: Jan Kara <[email protected]>
Abusing rq->csd.list for a list of requests to complete is rather ugly.
We use rq->queuelist instead which is much cleaner. It is safe because
queuelist is used by the block layer only for requests waiting to be
submitted to a device. Thus it is unused when irq reports the request IO
is finished.
Signed-off-by: Jan Kara <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
---
block/blk-softirq.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index 57790c1..b5c37d9 100644
--- a/block/blk-softirq.c
+++ b/block/blk-softirq.c
@@ -30,8 +30,8 @@ static void blk_done_softirq(struct softirq_action *h)
while (!list_empty(&local_list)) {
struct request *rq;
- rq = list_entry(local_list.next, struct request, csd.list);
- list_del_init(&rq->csd.list);
+ rq = list_entry(local_list.next, struct request, queuelist);
+ list_del_init(&rq->queuelist);
rq->q->softirq_done_fn(rq);
}
}
@@ -45,9 +45,14 @@ static void trigger_softirq(void *data)
local_irq_save(flags);
list = this_cpu_ptr(&blk_cpu_done);
- list_add_tail(&rq->csd.list, list);
+ /*
+ * We reuse queuelist for a list of requests to process. Since the
+ * queuelist is used by the block layer only for requests waiting to be
+ * submitted to the device it is unused now.
+ */
+ list_add_tail(&rq->queuelist, list);
- if (list->next == &rq->csd.list)
+ if (list->next == &rq->queuelist)
raise_softirq_irqoff(BLOCK_SOFTIRQ);
local_irq_restore(flags);
@@ -136,7 +141,7 @@ void __blk_complete_request(struct request *req)
struct list_head *list;
do_local:
list = this_cpu_ptr(&blk_cpu_done);
- list_add_tail(&req->csd.list, list);
+ list_add_tail(&req->queuelist, list);
/*
* if the list only contains our just added request,
@@ -144,7 +149,7 @@ do_local:
* entries there, someone already raised the irq but it
* hasn't run yet.
*/
- if (list->next == &req->csd.list)
+ if (list->next == &req->queuelist)
raise_softirq_irqoff(BLOCK_SOFTIRQ);
} else if (raise_blk_irq(ccpu, req))
goto do_local;
--
1.8.3.1
From: Jan Kara <[email protected]>
Now that we got rid of all the remaining code which fiddled with csd.list,
lets remove it.
Signed-off-by: Jan Kara <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
---
include/linux/smp.h | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/include/linux/smp.h b/include/linux/smp.h
index 3834f43..9a1b8ba 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -17,10 +17,7 @@ extern void cpu_idle(void);
typedef void (*smp_call_func_t)(void *info);
struct call_single_data {
- union {
- struct list_head list;
- struct llist_node llist;
- };
+ struct llist_node llist;
smp_call_func_t func;
void *info;
u16 flags;
--
1.8.3.1
From: Jan Kara <[email protected]>
Block layer currently abuses rq->csd.list.next for storing fifo_time.
That is a terrible hack and completely unnecessary as well. Union
achieves the same space saving in a cleaner way.
Signed-off-by: Jan Kara <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
---
block/cfq-iosched.c | 8 ++++----
block/deadline-iosched.c | 8 ++++----
include/linux/blkdev.h | 1 +
include/linux/elevator.h | 6 ------
4 files changed, 9 insertions(+), 14 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 744833b..5873e4a 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2367,10 +2367,10 @@ cfq_merged_requests(struct request_queue *q, struct request *rq,
* reposition in fifo if next is older than rq
*/
if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
- time_before(rq_fifo_time(next), rq_fifo_time(rq)) &&
+ time_before(next->fifo_time, rq->fifo_time) &&
cfqq == RQ_CFQQ(next)) {
list_move(&rq->queuelist, &next->queuelist);
- rq_set_fifo_time(rq, rq_fifo_time(next));
+ rq->fifo_time = next->fifo_time;
}
if (cfqq->next_rq == next)
@@ -2814,7 +2814,7 @@ static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
return NULL;
rq = rq_entry_fifo(cfqq->fifo.next);
- if (time_before(jiffies, rq_fifo_time(rq)))
+ if (time_before(jiffies, rq->fifo_time))
rq = NULL;
cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
@@ -3927,7 +3927,7 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq)
cfq_log_cfqq(cfqd, cfqq, "insert_request");
cfq_init_prio_data(cfqq, RQ_CIC(rq));
- rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
+ rq->fifo_time = jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)];
list_add_tail(&rq->queuelist, &cfqq->fifo);
cfq_add_rq_rb(rq);
cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index 9ef6640..a753df2 100644
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -106,7 +106,7 @@ deadline_add_request(struct request_queue *q, struct request *rq)
/*
* set expire time and add to fifo list
*/
- rq_set_fifo_time(rq, jiffies + dd->fifo_expire[data_dir]);
+ rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
}
@@ -174,9 +174,9 @@ deadline_merged_requests(struct request_queue *q, struct request *req,
* and move into next position (next will be deleted) in fifo
*/
if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
- if (time_before(rq_fifo_time(next), rq_fifo_time(req))) {
+ if (time_before(next->fifo_time, req->fifo_time)) {
list_move(&req->queuelist, &next->queuelist);
- rq_set_fifo_time(req, rq_fifo_time(next));
+ req->fifo_time = next->fifo_time;
}
}
@@ -230,7 +230,7 @@ static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
/*
* rq is expired!
*/
- if (time_after_eq(jiffies, rq_fifo_time(rq)))
+ if (time_after_eq(jiffies, rq->fifo_time))
return 1;
return 0;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 8678c43..dda98e3 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -99,6 +99,7 @@ struct request {
union {
struct call_single_data csd;
struct work_struct mq_flush_data;
+ unsigned long fifo_time;
};
struct request_queue *q;
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 306dd8c..0bdfd46 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -202,12 +202,6 @@ enum {
#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
-/*
- * Hack to reuse the csd.list list_head as the fifo time holder while
- * the request is in the io scheduler. Saves an unsigned long in rq.
- */
-#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
-#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
#define rq_fifo_clear(rq) do { \
list_del_init(&(rq)->queuelist); \
--
1.8.3.1
Might be worth to give the function a saner name than just the __-prefix
if you touch all callers anyway.
On Sat, Feb 08, 2014 at 08:42:47AM -0800, Christoph Hellwig wrote:
> Might be worth to give the function a saner name than just the __-prefix
> if you touch all callers anyway.
>
Good point. How about smp_call_function_single_async() ?
On Sat, Feb 08, 2014 at 05:46:36PM +0100, Frederic Weisbecker wrote:
> Good point. How about smp_call_function_single_async() ?
Fine with me.
On Sat 08-02-14 17:18:38, Frederic Weisbecker wrote:
> In order to remotely restart the watchdog hrtimer, update_timers()
> allocates a csd on the stack and pass it to __smp_call_function_single().
>
> There is no partcular need, however, for a specific csd here. Lets
> simplify that a little by calling smp_call_function_single()
> which can already take care of the csd allocation by itself.
>
> Cc: Andrew Morton <[email protected]>
> Cc: Christoph Hellwig <[email protected]>
> Cc: Don Zickus <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Jan Kara <[email protected]>
> Cc: Jens Axboe <[email protected]>
> Cc: Michal Hocko <[email protected]>
> Cc: Srivatsa S. Bhat <[email protected]>
> Signed-off-by: Frederic Weisbecker <[email protected]>
Looks good to me.
Reviewed-by: Michal Hocko <[email protected]>
> ---
> kernel/watchdog.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/kernel/watchdog.c b/kernel/watchdog.c
> index 4431610..01c6f97 100644
> --- a/kernel/watchdog.c
> +++ b/kernel/watchdog.c
> @@ -505,7 +505,6 @@ static void restart_watchdog_hrtimer(void *info)
>
> static void update_timers(int cpu)
> {
> - struct call_single_data data = {.func = restart_watchdog_hrtimer};
> /*
> * Make sure that perf event counter will adopt to a new
> * sampling period. Updating the sampling period directly would
> @@ -515,7 +514,7 @@ static void update_timers(int cpu)
> * might be late already so we have to restart the timer as well.
> */
> watchdog_nmi_disable(cpu);
> - __smp_call_function_single(cpu, &data, 1);
> + smp_call_function_single(cpu, restart_watchdog_hrtimer, NULL, 1);
> watchdog_nmi_enable(cpu);
> }
>
> --
> 1.8.3.1
>
--
Michal Hocko
SUSE Labs
On Sat, Feb 08, 2014 at 05:18:38PM +0100, Frederic Weisbecker wrote:
> In order to remotely restart the watchdog hrtimer, update_timers()
> allocates a csd on the stack and pass it to __smp_call_function_single().
>
> There is no partcular need, however, for a specific csd here. Lets
> simplify that a little by calling smp_call_function_single()
> which can already take care of the csd allocation by itself.
Sounds simple enough.
Acked-by: Don Zickus <[email protected]>
>
> Cc: Andrew Morton <[email protected]>
> Cc: Christoph Hellwig <[email protected]>
> Cc: Don Zickus <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Jan Kara <[email protected]>
> Cc: Jens Axboe <[email protected]>
> Cc: Michal Hocko <[email protected]>
> Cc: Srivatsa S. Bhat <[email protected]>
> Signed-off-by: Frederic Weisbecker <[email protected]>
> ---
> kernel/watchdog.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/kernel/watchdog.c b/kernel/watchdog.c
> index 4431610..01c6f97 100644
> --- a/kernel/watchdog.c
> +++ b/kernel/watchdog.c
> @@ -505,7 +505,6 @@ static void restart_watchdog_hrtimer(void *info)
>
> static void update_timers(int cpu)
> {
> - struct call_single_data data = {.func = restart_watchdog_hrtimer};
> /*
> * Make sure that perf event counter will adopt to a new
> * sampling period. Updating the sampling period directly would
> @@ -515,7 +514,7 @@ static void update_timers(int cpu)
> * might be late already so we have to restart the timer as well.
> */
> watchdog_nmi_disable(cpu);
> - __smp_call_function_single(cpu, &data, 1);
> + smp_call_function_single(cpu, restart_watchdog_hrtimer, NULL, 1);
> watchdog_nmi_enable(cpu);
> }
>
> --
> 1.8.3.1
>
On Sat 08-02-14 17:18:31, Frederic Weisbecker wrote:
> rq_fifo_clear() reset the csd.list through INIT_LIST_HEAD for no clear
> purpose. The csd.list doesn't need to be initialized as a list head
> because it's only ever used as a list node.
>
> Lets remove this useless initialization.
>
> Cc: Andrew Morton <[email protected]>
> Cc: Christoph Hellwig <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Jan Kara <[email protected]>
> Cc: Jens Axboe <[email protected]>
> Signed-off-by: Frederic Weisbecker <[email protected]>
Looks good. You can add:
Reviewed-by: Jan Kara <[email protected]>
Honza
> ---
> include/linux/elevator.h | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/include/linux/elevator.h b/include/linux/elevator.h
> index 0bdfd46..df63bd3 100644
> --- a/include/linux/elevator.h
> +++ b/include/linux/elevator.h
> @@ -203,10 +203,7 @@ enum {
> #define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
>
> #define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
> -#define rq_fifo_clear(rq) do { \
> - list_del_init(&(rq)->queuelist); \
> - INIT_LIST_HEAD(&(rq)->csd.list); \
> - } while (0)
> +#define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
>
> #else /* CONFIG_BLOCK */
>
> --
> 1.8.3.1
>
--
Jan Kara <[email protected]>
SUSE Labs, CR
On Sat 08-02-14 17:18:36, Frederic Weisbecker wrote:
> __smp_call_function_single() and smp_call_function_single() share some
> code that can be factorized: execute inline when the target is local,
> check if the target is online, lock the csd, call generic_exec_single().
>
> Lets move the common parts to generic_exec_single().
The patch looks good. You can add:
Reviewed-by: Jan Kara <[email protected]>
Honza
>
> Cc: Andrew Morton <[email protected]>
> Cc: Christoph Hellwig <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Jan Kara <[email protected]>
> Cc: Jens Axboe <[email protected]>
> Signed-off-by: Frederic Weisbecker <[email protected]>
> ---
> kernel/smp.c | 80 +++++++++++++++++++++++++++++-------------------------------
> 1 file changed, 39 insertions(+), 41 deletions(-)
>
> diff --git a/kernel/smp.c b/kernel/smp.c
> index 5ff14e3..64bb0d4 100644
> --- a/kernel/smp.c
> +++ b/kernel/smp.c
> @@ -117,13 +117,43 @@ static void csd_unlock(struct call_single_data *csd)
> csd->flags &= ~CSD_FLAG_LOCK;
> }
>
> +static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
> +
> /*
> * Insert a previously allocated call_single_data element
> * for execution on the given CPU. data must already have
> * ->func, ->info, and ->flags set.
> */
> -static void generic_exec_single(int cpu, struct call_single_data *csd, int wait)
> +static int generic_exec_single(int cpu, struct call_single_data *csd,
> + smp_call_func_t func, void *info, int wait)
> {
> + struct call_single_data csd_stack = { .flags = 0 };
> + unsigned long flags;
> +
> +
> + if (cpu == smp_processor_id()) {
> + local_irq_save(flags);
> + func(info);
> + local_irq_restore(flags);
> + return 0;
> + }
> +
> +
> + if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu))
> + return -ENXIO;
> +
> +
> + if (!csd) {
> + csd = &csd_stack;
> + if (!wait)
> + csd = &__get_cpu_var(csd_data);
> + }
> +
> + csd_lock(csd);
> +
> + csd->func = func;
> + csd->info = info;
> +
> if (wait)
> csd->flags |= CSD_FLAG_WAIT;
>
> @@ -143,6 +173,8 @@ static void generic_exec_single(int cpu, struct call_single_data *csd, int wait)
>
> if (wait)
> csd_lock_wait(csd);
> +
> + return 0;
> }
>
> /*
> @@ -168,8 +200,6 @@ void generic_smp_call_function_single_interrupt(void)
> }
> }
>
> -static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
> -
> /*
> * smp_call_function_single - Run a function on a specific CPU
> * @func: The function to run. This must be fast and non-blocking.
> @@ -181,12 +211,8 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
> int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
> int wait)
> {
> - struct call_single_data d = {
> - .flags = 0,
> - };
> - unsigned long flags;
> int this_cpu;
> - int err = 0;
> + int err;
>
> /*
> * prevent preemption and reschedule on another processor,
> @@ -203,26 +229,7 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
> WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
> && !oops_in_progress);
>
> - if (cpu == this_cpu) {
> - local_irq_save(flags);
> - func(info);
> - local_irq_restore(flags);
> - } else {
> - if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
> - struct call_single_data *csd = &d;
> -
> - if (!wait)
> - csd = &__get_cpu_var(csd_data);
> -
> - csd_lock(csd);
> -
> - csd->func = func;
> - csd->info = info;
> - generic_exec_single(cpu, csd, wait);
> - } else {
> - err = -ENXIO; /* CPU not online */
> - }
> - }
> + err = generic_exec_single(cpu, NULL, func, info, wait);
>
> put_cpu();
>
> @@ -285,9 +292,8 @@ EXPORT_SYMBOL_GPL(smp_call_function_any);
> */
> int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
> {
> - unsigned int this_cpu;
> - unsigned long flags;
> int err = 0;
> + int this_cpu;
>
> this_cpu = get_cpu();
> /*
> @@ -296,20 +302,12 @@ int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
> * send smp call function interrupt to this cpu and as such deadlocks
> * can't happen.
> */
> - WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled()
> + WARN_ON_ONCE(cpu_online(this_cpu) && wait && irqs_disabled()
> && !oops_in_progress);
>
> - if (cpu == this_cpu) {
> - local_irq_save(flags);
> - csd->func(csd->info);
> - local_irq_restore(flags);
> - } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
> - csd_lock(csd);
> - generic_exec_single(cpu, csd, wait);
> - } else {
> - err = -ENXIO; /* CPU not online */
> - }
> + err = generic_exec_single(cpu, csd, csd->func, csd->info, wait);
> put_cpu();
> +
> return err;
> }
> EXPORT_SYMBOL_GPL(__smp_call_function_single);
> --
> 1.8.3.1
>
--
Jan Kara <[email protected]>
SUSE Labs, CR
On Sat 08-02-14 17:18:37, Frederic Weisbecker wrote:
> Move this function closer to __smp_call_function_single(). These functions
> have very similar behavior and should be displayed in the same block
> for clarity.
Whatever :). You can add:
Reviewed-by: Jan Kara <[email protected]>
Honza
>
> Cc: Andrew Morton <[email protected]>
> Cc: Christoph Hellwig <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Jan Kara <[email protected]>
> Cc: Jens Axboe <[email protected]>
> Signed-off-by: Frederic Weisbecker <[email protected]>
> ---
> kernel/smp.c | 64 ++++++++++++++++++++++++++++++------------------------------
> 1 file changed, 32 insertions(+), 32 deletions(-)
>
> diff --git a/kernel/smp.c b/kernel/smp.c
> index 64bb0d4..fa04ab9 100644
> --- a/kernel/smp.c
> +++ b/kernel/smp.c
> @@ -237,6 +237,38 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
> }
> EXPORT_SYMBOL(smp_call_function_single);
>
> +/**
> + * __smp_call_function_single(): Run a function on a specific CPU
> + * @cpu: The CPU to run on.
> + * @csd: Pre-allocated and setup data structure
> + * @wait: If true, wait until function has completed on specified CPU.
> + *
> + * Like smp_call_function_single(), but allow caller to pass in a
> + * pre-allocated data structure. Useful for embedding @data inside
> + * other structures, for instance.
> + */
> +int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
> +{
> + int err = 0;
> + int this_cpu;
> +
> + this_cpu = get_cpu();
> + /*
> + * Can deadlock when called with interrupts disabled.
> + * We allow cpu's that are not yet online though, as no one else can
> + * send smp call function interrupt to this cpu and as such deadlocks
> + * can't happen.
> + */
> + WARN_ON_ONCE(cpu_online(this_cpu) && wait && irqs_disabled()
> + && !oops_in_progress);
> +
> + err = generic_exec_single(cpu, csd, csd->func, csd->info, wait);
> + put_cpu();
> +
> + return err;
> +}
> +EXPORT_SYMBOL_GPL(__smp_call_function_single);
> +
> /*
> * smp_call_function_any - Run a function on any of the given cpus
> * @mask: The mask of cpus it can run on.
> @@ -281,38 +313,6 @@ call:
> EXPORT_SYMBOL_GPL(smp_call_function_any);
>
> /**
> - * __smp_call_function_single(): Run a function on a specific CPU
> - * @cpu: The CPU to run on.
> - * @csd: Pre-allocated and setup data structure
> - * @wait: If true, wait until function has completed on specified CPU.
> - *
> - * Like smp_call_function_single(), but allow caller to pass in a
> - * pre-allocated data structure. Useful for embedding @data inside
> - * other structures, for instance.
> - */
> -int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
> -{
> - int err = 0;
> - int this_cpu;
> -
> - this_cpu = get_cpu();
> - /*
> - * Can deadlock when called with interrupts disabled.
> - * We allow cpu's that are not yet online though, as no one else can
> - * send smp call function interrupt to this cpu and as such deadlocks
> - * can't happen.
> - */
> - WARN_ON_ONCE(cpu_online(this_cpu) && wait && irqs_disabled()
> - && !oops_in_progress);
> -
> - err = generic_exec_single(cpu, csd, csd->func, csd->info, wait);
> - put_cpu();
> -
> - return err;
> -}
> -EXPORT_SYMBOL_GPL(__smp_call_function_single);
> -
> -/**
> * smp_call_function_many(): Run a function on a set of other CPUs.
> * @mask: The set of cpus to run on (only runs on online subset).
> * @func: The function to run. This must be fast and non-blocking.
> --
> 1.8.3.1
>
--
Jan Kara <[email protected]>
SUSE Labs, CR