None of the relay users require the use of mutable structs for
callbacks, however the relay code does. Instead of assigning default
callbacks when there is none, add callback wrappers to conditionally
call the client callbacks if available, and fall back to default
behaviour (typically no-op) otherwise.
This lets all relay users make their struct rchan_callbacks const data.
Cc: [email protected]
Cc: Jens Axboe <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Kalle Valo <[email protected]>
Cc: [email protected]
Cc: QCA ath9k Development <[email protected]>
Cc: [email protected]
Signed-off-by: Jani Nikula <[email protected]>
---
include/linux/relay.h | 4 +-
kernel/relay.c | 182 +++++++++++++++++++-----------------------
2 files changed, 86 insertions(+), 100 deletions(-)
diff --git a/include/linux/relay.h b/include/linux/relay.h
index e13a333e7c37..7333909df65a 100644
--- a/include/linux/relay.h
+++ b/include/linux/relay.h
@@ -62,7 +62,7 @@ struct rchan
size_t subbuf_size; /* sub-buffer size */
size_t n_subbufs; /* number of sub-buffers per buffer */
size_t alloc_size; /* total buffer size allocated */
- struct rchan_callbacks *cb; /* client callbacks */
+ const struct rchan_callbacks *cb; /* client callbacks, may be NULL */
struct kref kref; /* channel refcount */
void *private_data; /* for user-defined data */
size_t last_toobig; /* tried to log event > subbuf size */
@@ -170,7 +170,7 @@ struct rchan *relay_open(const char *base_filename,
struct dentry *parent,
size_t subbuf_size,
size_t n_subbufs,
- struct rchan_callbacks *cb,
+ const struct rchan_callbacks *cb,
void *private_data);
extern int relay_late_setup_files(struct rchan *chan,
const char *base_filename,
diff --git a/kernel/relay.c b/kernel/relay.c
index b08d936d5fa7..c53676f2d10f 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -27,13 +27,86 @@
static DEFINE_MUTEX(relay_channels_mutex);
static LIST_HEAD(relay_channels);
+/*
+ * rchan_callback wrappers. Call the callbacks if available, otherwise fall back
+ * to default behaviour.
+ */
+
+/*
+ * subbuf_start() callback.
+ */
+static int cb_subbuf_start(const struct rchan_callbacks *cb,
+ struct rchan_buf *buf,
+ void *subbuf,
+ void *prev_subbuf,
+ size_t prev_padding)
+{
+ if (cb && cb->subbuf_start)
+ return cb->subbuf_start(buf, subbuf, prev_subbuf, prev_padding);
+
+ if (relay_buf_full(buf))
+ return 0;
+
+ return 1;
+}
+
+/*
+ * buf_mapped() callback.
+ */
+static void cb_buf_mapped(const struct rchan_callbacks *cb,
+ struct rchan_buf *buf,
+ struct file *filp)
+{
+ if (cb && cb->buf_mapped)
+ cb->buf_mapped(buf, filp);
+}
+
+/*
+ * buf_unmapped() callback.
+ */
+static void cb_buf_unmapped(const struct rchan_callbacks *cb,
+ struct rchan_buf *buf,
+ struct file *filp)
+{
+ if (cb && cb->buf_unmapped)
+ cb->buf_unmapped(buf, filp);
+}
+
+/*
+ * create_buf_file_create() callback.
+ */
+static struct dentry *cb_create_buf_file(const struct rchan_callbacks *cb,
+ const char *filename,
+ struct dentry *parent,
+ umode_t mode,
+ struct rchan_buf *buf,
+ int *is_global)
+{
+ if (cb && cb->create_buf_file)
+ return cb->create_buf_file(filename, parent, mode, buf, is_global);
+
+ return NULL;
+}
+
+/*
+ * remove_buf_file() callback.
+ */
+static int cb_remove_buf_file(const struct rchan_callbacks *cb,
+ struct dentry *dentry)
+{
+ if (cb && cb->remove_buf_file)
+ return cb->remove_buf_file(dentry);
+
+ return -EINVAL;
+}
+
/*
* close() vm_op implementation for relay file mapping.
*/
static void relay_file_mmap_close(struct vm_area_struct *vma)
{
struct rchan_buf *buf = vma->vm_private_data;
- buf->chan->cb->buf_unmapped(buf, vma->vm_file);
+ cb_buf_unmapped(buf->chan->cb, buf, vma->vm_file);
}
/*
@@ -107,7 +180,7 @@ static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma)
vma->vm_ops = &relay_file_mmap_ops;
vma->vm_flags |= VM_DONTEXPAND;
vma->vm_private_data = buf;
- buf->chan->cb->buf_mapped(buf, filp);
+ cb_buf_mapped(buf->chan->cb, buf, filp);
return 0;
}
@@ -264,70 +337,6 @@ EXPORT_SYMBOL_GPL(relay_buf_full);
* High-level relay kernel API and associated functions.
*/
-/*
- * rchan_callback implementations defining default channel behavior. Used
- * in place of corresponding NULL values in client callback struct.
- */
-
-/*
- * subbuf_start() default callback. Does nothing.
- */
-static int subbuf_start_default_callback (struct rchan_buf *buf,
- void *subbuf,
- void *prev_subbuf,
- size_t prev_padding)
-{
- if (relay_buf_full(buf))
- return 0;
-
- return 1;
-}
-
-/*
- * buf_mapped() default callback. Does nothing.
- */
-static void buf_mapped_default_callback(struct rchan_buf *buf,
- struct file *filp)
-{
-}
-
-/*
- * buf_unmapped() default callback. Does nothing.
- */
-static void buf_unmapped_default_callback(struct rchan_buf *buf,
- struct file *filp)
-{
-}
-
-/*
- * create_buf_file_create() default callback. Does nothing.
- */
-static struct dentry *create_buf_file_default_callback(const char *filename,
- struct dentry *parent,
- umode_t mode,
- struct rchan_buf *buf,
- int *is_global)
-{
- return NULL;
-}
-
-/*
- * remove_buf_file() default callback. Does nothing.
- */
-static int remove_buf_file_default_callback(struct dentry *dentry)
-{
- return -EINVAL;
-}
-
-/* relay channel default callbacks */
-static struct rchan_callbacks default_channel_callbacks = {
- .subbuf_start = subbuf_start_default_callback,
- .buf_mapped = buf_mapped_default_callback,
- .buf_unmapped = buf_unmapped_default_callback,
- .create_buf_file = create_buf_file_default_callback,
- .remove_buf_file = remove_buf_file_default_callback,
-};
-
/**
* wakeup_readers - wake up readers waiting on a channel
* @work: contains the channel buffer
@@ -371,7 +380,7 @@ static void __relay_reset(struct rchan_buf *buf, unsigned int init)
for (i = 0; i < buf->chan->n_subbufs; i++)
buf->padding[i] = 0;
- buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0);
+ cb_subbuf_start(buf->chan->cb, buf, buf->data, NULL, 0);
}
/**
@@ -426,9 +435,8 @@ static struct dentry *relay_create_buf_file(struct rchan *chan,
snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu);
/* Create file in fs */
- dentry = chan->cb->create_buf_file(tmpname, chan->parent,
- S_IRUSR, buf,
- &chan->is_global);
+ dentry = cb_create_buf_file(chan->cb, tmpname, chan->parent,
+ S_IRUSR, buf, &chan->is_global);
if (IS_ERR(dentry))
dentry = NULL;
@@ -461,9 +469,8 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
relay_set_buf_dentry(buf, dentry);
} else {
/* Only retrieve global info, nothing more, nothing less */
- dentry = chan->cb->create_buf_file(NULL, NULL,
- S_IRUSR, buf,
- &chan->is_global);
+ dentry = cb_create_buf_file(chan->cb, NULL, NULL,
+ S_IRUSR, buf, &chan->is_global);
if (IS_ERR_OR_NULL(dentry))
goto free_buf;
}
@@ -495,31 +502,10 @@ static void relay_close_buf(struct rchan_buf *buf)
{
buf->finalized = 1;
irq_work_sync(&buf->wakeup_work);
- buf->chan->cb->remove_buf_file(buf->dentry);
+ cb_remove_buf_file(buf->chan->cb, buf->dentry);
kref_put(&buf->kref, relay_remove_buf);
}
-static void setup_callbacks(struct rchan *chan,
- struct rchan_callbacks *cb)
-{
- if (!cb) {
- chan->cb = &default_channel_callbacks;
- return;
- }
-
- if (!cb->subbuf_start)
- cb->subbuf_start = subbuf_start_default_callback;
- if (!cb->buf_mapped)
- cb->buf_mapped = buf_mapped_default_callback;
- if (!cb->buf_unmapped)
- cb->buf_unmapped = buf_unmapped_default_callback;
- if (!cb->create_buf_file)
- cb->create_buf_file = create_buf_file_default_callback;
- if (!cb->remove_buf_file)
- cb->remove_buf_file = remove_buf_file_default_callback;
- chan->cb = cb;
-}
-
int relay_prepare_cpu(unsigned int cpu)
{
struct rchan *chan;
@@ -565,7 +551,7 @@ struct rchan *relay_open(const char *base_filename,
struct dentry *parent,
size_t subbuf_size,
size_t n_subbufs,
- struct rchan_callbacks *cb,
+ const struct rchan_callbacks *cb,
void *private_data)
{
unsigned int i;
@@ -597,7 +583,7 @@ struct rchan *relay_open(const char *base_filename,
chan->has_base_filename = 1;
strlcpy(chan->base_filename, base_filename, NAME_MAX);
}
- setup_callbacks(chan, cb);
+ chan->cb = cb;
kref_init(&chan->kref);
mutex_lock(&relay_channels_mutex);
@@ -780,7 +766,7 @@ size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
new = buf->start + new_subbuf * buf->chan->subbuf_size;
buf->offset = 0;
- if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) {
+ if (!cb_subbuf_start(buf->chan->cb, buf, new, old, buf->prev_padding)) {
buf->offset = buf->chan->subbuf_size + 1;
return 0;
}
--
2.20.1
Now that relay_open() accepts const callbacks, make relay callbacks
const.
Cc: [email protected]
Signed-off-by: Jani Nikula <[email protected]>
---
drivers/gpu/drm/i915/gt/uc/intel_guc_log.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c
index 9bbe8a795cb8..c92f2c056db4 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c
@@ -134,7 +134,7 @@ static int remove_buf_file_callback(struct dentry *dentry)
}
/* relay channel callbacks */
-static struct rchan_callbacks relay_callbacks = {
+static const struct rchan_callbacks relay_callbacks = {
.subbuf_start = subbuf_start_callback,
.create_buf_file = create_buf_file_callback,
.remove_buf_file = remove_buf_file_callback,
--
2.20.1
Now that relay_open() accepts const callbacks, make relay callbacks
const.
Cc: Jens Axboe <[email protected]>
Cc: [email protected]
Signed-off-by: Jani Nikula <[email protected]>
---
kernel/trace/blktrace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index f1022945e346..b5c4b9ade960 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -449,7 +449,7 @@ static struct dentry *blk_create_buf_file_callback(const char *filename,
&relay_file_operations);
}
-static struct rchan_callbacks blk_relay_callbacks = {
+static const struct rchan_callbacks blk_relay_callbacks = {
.subbuf_start = blk_subbuf_start_callback,
.create_buf_file = blk_create_buf_file_callback,
.remove_buf_file = blk_remove_buf_file_callback,
--
2.20.1
Now that relay_open() accepts const callbacks, make relay callbacks
const.
Cc: Kalle Valo <[email protected]>
Cc: [email protected]
Signed-off-by: Jani Nikula <[email protected]>
---
drivers/net/wireless/ath/ath10k/spectral.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/wireless/ath/ath10k/spectral.c b/drivers/net/wireless/ath/ath10k/spectral.c
index 5db6bff5193b..68254a967ccb 100644
--- a/drivers/net/wireless/ath/ath10k/spectral.c
+++ b/drivers/net/wireless/ath/ath10k/spectral.c
@@ -497,7 +497,7 @@ static int remove_buf_file_handler(struct dentry *dentry)
return 0;
}
-static struct rchan_callbacks rfs_spec_scan_cb = {
+static const struct rchan_callbacks rfs_spec_scan_cb = {
.create_buf_file = create_buf_file_handler,
.remove_buf_file = remove_buf_file_handler,
};
--
2.20.1
Now that relay_open() accepts const callbacks, make relay callbacks
const.
Cc: Kalle Valo <[email protected]>
Cc: [email protected]
Signed-off-by: Jani Nikula <[email protected]>
---
drivers/net/wireless/ath/ath11k/spectral.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/wireless/ath/ath11k/spectral.c b/drivers/net/wireless/ath/ath11k/spectral.c
index ac2a8cfdc1c0..1afe67759659 100644
--- a/drivers/net/wireless/ath/ath11k/spectral.c
+++ b/drivers/net/wireless/ath/ath11k/spectral.c
@@ -148,7 +148,7 @@ static int remove_buf_file_handler(struct dentry *dentry)
return 0;
}
-static struct rchan_callbacks rfs_scan_cb = {
+static const struct rchan_callbacks rfs_scan_cb = {
.create_buf_file = create_buf_file_handler,
.remove_buf_file = remove_buf_file_handler,
};
--
2.20.1
Jani Nikula <[email protected]> writes:
> Now that relay_open() accepts const callbacks, make relay callbacks
> const.
>
> Cc: Kalle Valo <[email protected]>
> Cc: [email protected]
> Signed-off-by: Jani Nikula <[email protected]>
I assume this goes via some other tree:
Acked-by: Kalle Valo <[email protected]>
--
https://patchwork.kernel.org/project/linux-wireless/list/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
> +/*
> + * rchan_callback wrappers. Call the callbacks if available, otherwise fall back
> + * to default behaviour.
> + */
This adds an overly long line. That being said this behavior is pretty
normal for kernel APIs, so I'm not even sure we need it at all.
> +
> +/*
> + * subbuf_start() callback.
> + */
and this one is for sure completley useless. Same for all the other
similar ones.
But taking one step back: All instances implement create_buf_file
and remove_buf_file, which makes sense as that is the prime aim
of these methods. So there is no point in making those optional.
subbuf_start_callback is overriden by two instances, so making that
optional totally makes sense. buf_mapped and buf_unmapped are
never overriden, so they should be removed entirely.
More importantly there is no case that passes a NULL rchan_callbacks,
which makes complete sense as it wouldn't even create a file. So
remove that case as well and just replace it with a sanity check in
relay_open().
Please also add a patch to mark all rchan_callbacks instances const
while you're at it.
On Wed, 18 Nov 2020, Jani Nikula <[email protected]> wrote:
> Now that relay_open() accepts const callbacks, make relay callbacks
> const.
>
> Cc: Kalle Valo <[email protected]>
> Cc: [email protected]
> Signed-off-by: Jani Nikula <[email protected]>
Kalle, thanks for the acks on the other two ath patches - can I have
your ack on this one too please?
BR,
Jani.
> ---
> drivers/net/wireless/ath/ath11k/spectral.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/ath/ath11k/spectral.c b/drivers/net/wireless/ath/ath11k/spectral.c
> index ac2a8cfdc1c0..1afe67759659 100644
> --- a/drivers/net/wireless/ath/ath11k/spectral.c
> +++ b/drivers/net/wireless/ath/ath11k/spectral.c
> @@ -148,7 +148,7 @@ static int remove_buf_file_handler(struct dentry *dentry)
> return 0;
> }
>
> -static struct rchan_callbacks rfs_scan_cb = {
> +static const struct rchan_callbacks rfs_scan_cb = {
> .create_buf_file = create_buf_file_handler,
> .remove_buf_file = remove_buf_file_handler,
> };
--
Jani Nikula, Intel Open Source Graphics Center
Jani Nikula <[email protected]> writes:
> On Wed, 18 Nov 2020, Jani Nikula <[email protected]> wrote:
>> Now that relay_open() accepts const callbacks, make relay callbacks
>> const.
>>
>> Cc: Kalle Valo <[email protected]>
>> Cc: [email protected]
>> Signed-off-by: Jani Nikula <[email protected]>
>
> Kalle, thanks for the acks on the other two ath patches - can I have
> your ack on this one too please?
Oops, missed that:
Acked-by: Kalle Valo <[email protected]>
--
https://patchwork.kernel.org/project/linux-wireless/list/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
On Thu, 19 Nov 2020, Christoph Hellwig <[email protected]> wrote:
> But taking one step back: All instances implement create_buf_file
> and remove_buf_file, which makes sense as that is the prime aim
> of these methods. So there is no point in making those optional.
> subbuf_start_callback is overriden by two instances, so making that
> optional totally makes sense. buf_mapped and buf_unmapped are
> never overriden, so they should be removed entirely.
>
> More importantly there is no case that passes a NULL rchan_callbacks,
> which makes complete sense as it wouldn't even create a file. So
> remove that case as well and just replace it with a sanity check in
> relay_open().
Many thanks for the feedback; sent v2 [1].
BR,
Jani.
[1] http://lore.kernel.org/r/[email protected]
--
Jani Nikula, Intel Open Source Graphics Center