This implements a new interface to lockedp, lock_set_cmp_fn(), for
defining an ordering when taking multiple locks of the same type.
This provides a more rigorous mechanism than the subclass mechanism -
it's hoped that this might be able to replace subclasses.
Signed-off-by: Kent Overstreet <[email protected]>
Cc: Peter Zijlstra <[email protected]> (maintainer:LOCKING PRIMITIVES)
Cc: Ingo Molnar <[email protected]> (maintainer:LOCKING PRIMITIVES)
Signed-off-by: Kent Overstreet <[email protected]>
---
include/linux/lockdep.h | 8 +++
include/linux/lockdep_types.h | 8 +++
kernel/locking/lockdep.c | 115 +++++++++++++++++++++++++---------
3 files changed, 101 insertions(+), 30 deletions(-)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 1023f349af..2b4497ee3d 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -379,6 +379,14 @@ static inline void lockdep_set_selftest_task(struct task_struct *task)
do { (void)(key); } while (0)
#define lockdep_set_subclass(lock, sub) do { } while (0)
+#ifdef CONFIG_PROVE_LOCKING
+void lockdep_set_lock_cmp_fn(struct lockdep_map *, lock_cmp_fn, lock_print_fn);
+
+#define lock_set_cmp_fn(lock, ...) lockdep_set_lock_cmp_fn(&(lock)->dep_map, __VA_ARGS__)
+#else
+#define lock_set_cmp_fn(lock, ...) do {} while (0)
+#endif
+
#define lockdep_set_novalidate_class(lock) do { } while (0)
/*
diff --git a/include/linux/lockdep_types.h b/include/linux/lockdep_types.h
index d22430840b..8bf79c4e48 100644
--- a/include/linux/lockdep_types.h
+++ b/include/linux/lockdep_types.h
@@ -84,6 +84,11 @@ struct lock_trace;
#define LOCKSTAT_POINTS 4
+struct lockdep_map;
+typedef int (*lock_cmp_fn)(const struct lockdep_map *a,
+ const struct lockdep_map *b);
+typedef void (*lock_print_fn)(const struct lockdep_map *map);
+
/*
* The lock-class itself. The order of the structure members matters.
* reinit_class() zeroes the key member and all subsequent members.
@@ -109,6 +114,9 @@ struct lock_class {
struct list_head locks_after, locks_before;
const struct lockdep_subclass_key *key;
+ lock_cmp_fn cmp_fn;
+ lock_print_fn print_fn;
+
unsigned int subclass;
unsigned int dep_gen_id;
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 50d4863974..7b8c16cbef 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -709,7 +709,7 @@ void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
usage[i] = '\0';
}
-static void __print_lock_name(struct lock_class *class)
+static void __print_lock_name(struct held_lock *hlock, struct lock_class *class)
{
char str[KSYM_NAME_LEN];
const char *name;
@@ -724,17 +724,19 @@ static void __print_lock_name(struct lock_class *class)
printk(KERN_CONT "#%d", class->name_version);
if (class->subclass)
printk(KERN_CONT "/%d", class->subclass);
+ if (hlock && class->print_fn)
+ class->print_fn(hlock->instance);
}
}
-static void print_lock_name(struct lock_class *class)
+static void print_lock_name(struct held_lock *hlock, struct lock_class *class)
{
char usage[LOCK_USAGE_CHARS];
get_usage_chars(class, usage);
printk(KERN_CONT " (");
- __print_lock_name(class);
+ __print_lock_name(hlock, class);
printk(KERN_CONT "){%s}-{%d:%d}", usage,
class->wait_type_outer ?: class->wait_type_inner,
class->wait_type_inner);
@@ -772,7 +774,7 @@ static void print_lock(struct held_lock *hlock)
}
printk(KERN_CONT "%px", hlock->instance);
- print_lock_name(lock);
+ print_lock_name(hlock, lock);
printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
}
@@ -1868,7 +1870,7 @@ print_circular_bug_entry(struct lock_list *target, int depth)
if (debug_locks_silent)
return;
printk("\n-> #%u", depth);
- print_lock_name(target->class);
+ print_lock_name(NULL, target->class);
printk(KERN_CONT ":\n");
print_lock_trace(target->trace, 6);
}
@@ -1897,11 +1899,11 @@ print_circular_lock_scenario(struct held_lock *src,
*/
if (parent != source) {
printk("Chain exists of:\n ");
- __print_lock_name(source);
+ __print_lock_name(src, source);
printk(KERN_CONT " --> ");
- __print_lock_name(parent);
+ __print_lock_name(NULL, parent);
printk(KERN_CONT " --> ");
- __print_lock_name(target);
+ __print_lock_name(tgt, target);
printk(KERN_CONT "\n\n");
}
@@ -1909,16 +1911,16 @@ print_circular_lock_scenario(struct held_lock *src,
printk(" CPU0 CPU1\n");
printk(" ---- ----\n");
printk(" lock(");
- __print_lock_name(target);
+ __print_lock_name(tgt, target);
printk(KERN_CONT ");\n");
printk(" lock(");
- __print_lock_name(parent);
+ __print_lock_name(NULL, parent);
printk(KERN_CONT ");\n");
printk(" lock(");
- __print_lock_name(target);
+ __print_lock_name(tgt, target);
printk(KERN_CONT ");\n");
printk(" lock(");
- __print_lock_name(source);
+ __print_lock_name(src, source);
printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
}
@@ -2144,6 +2146,8 @@ check_path(struct held_lock *target, struct lock_list *src_entry,
return ret;
}
+static void print_deadlock_bug(struct task_struct *, struct held_lock *, struct held_lock *);
+
/*
* Prove that the dependency graph starting at <src> can not
* lead to <target>. If it can, there is a circle when adding
@@ -2175,7 +2179,10 @@ check_noncircular(struct held_lock *src, struct held_lock *target,
*trace = save_trace();
}
- print_circular_bug(&src_entry, target_entry, src, target);
+ if (src->class_idx == target->class_idx)
+ print_deadlock_bug(current, src, target);
+ else
+ print_circular_bug(&src_entry, target_entry, src, target);
}
return ret;
@@ -2331,7 +2338,7 @@ static void print_lock_class_header(struct lock_class *class, int depth)
int bit;
printk("%*s->", depth, "");
- print_lock_name(class);
+ print_lock_name(NULL, class);
#ifdef CONFIG_DEBUG_LOCKDEP
printk(KERN_CONT " ops: %lu", debug_class_ops_read(class));
#endif
@@ -2513,11 +2520,11 @@ print_irq_lock_scenario(struct lock_list *safe_entry,
*/
if (middle_class != unsafe_class) {
printk("Chain exists of:\n ");
- __print_lock_name(safe_class);
+ __print_lock_name(NULL, safe_class);
printk(KERN_CONT " --> ");
- __print_lock_name(middle_class);
+ __print_lock_name(NULL, middle_class);
printk(KERN_CONT " --> ");
- __print_lock_name(unsafe_class);
+ __print_lock_name(NULL, unsafe_class);
printk(KERN_CONT "\n\n");
}
@@ -2525,18 +2532,18 @@ print_irq_lock_scenario(struct lock_list *safe_entry,
printk(" CPU0 CPU1\n");
printk(" ---- ----\n");
printk(" lock(");
- __print_lock_name(unsafe_class);
+ __print_lock_name(NULL, unsafe_class);
printk(KERN_CONT ");\n");
printk(" local_irq_disable();\n");
printk(" lock(");
- __print_lock_name(safe_class);
+ __print_lock_name(NULL, safe_class);
printk(KERN_CONT ");\n");
printk(" lock(");
- __print_lock_name(middle_class);
+ __print_lock_name(NULL, middle_class);
printk(KERN_CONT ");\n");
printk(" <Interrupt>\n");
printk(" lock(");
- __print_lock_name(safe_class);
+ __print_lock_name(NULL, safe_class);
printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
}
@@ -2573,20 +2580,20 @@ print_bad_irq_dependency(struct task_struct *curr,
pr_warn("\nand this task is already holding:\n");
print_lock(prev);
pr_warn("which would create a new lock dependency:\n");
- print_lock_name(hlock_class(prev));
+ print_lock_name(prev, hlock_class(prev));
pr_cont(" ->");
- print_lock_name(hlock_class(next));
+ print_lock_name(next, hlock_class(next));
pr_cont("\n");
pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
irqclass);
- print_lock_name(backwards_entry->class);
+ print_lock_name(NULL, backwards_entry->class);
pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
print_lock_trace(backwards_entry->class->usage_traces[bit1], 1);
pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
- print_lock_name(forwards_entry->class);
+ print_lock_name(NULL, forwards_entry->class);
pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
pr_warn("...");
@@ -2956,10 +2963,10 @@ print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
printk(" CPU0\n");
printk(" ----\n");
printk(" lock(");
- __print_lock_name(prev);
+ __print_lock_name(prv, prev);
printk(KERN_CONT ");\n");
printk(" lock(");
- __print_lock_name(next);
+ __print_lock_name(nxt, next);
printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
printk(" May be due to missing lock nesting notation\n\n");
@@ -2969,6 +2976,8 @@ static void
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
struct held_lock *next)
{
+ struct lock_class *class = hlock_class(prev);
+
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return;
@@ -2983,6 +2992,10 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
pr_warn("\nbut task is already holding lock:\n");
print_lock(prev);
+ if (class->cmp_fn)
+ pr_warn("and the lock comparison function returns %i:\n",
+ class->cmp_fn(prev->instance, next->instance));
+
pr_warn("\nother info that might help us debug this:\n");
print_deadlock_scenario(next, prev);
lockdep_print_held_locks(curr);
@@ -3004,6 +3017,7 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
static int
check_deadlock(struct task_struct *curr, struct held_lock *next)
{
+ struct lock_class *class;
struct held_lock *prev;
struct held_lock *nest = NULL;
int i;
@@ -3024,6 +3038,12 @@ check_deadlock(struct task_struct *curr, struct held_lock *next)
if ((next->read == 2) && prev->read)
continue;
+ class = hlock_class(prev);
+
+ if (class->cmp_fn &&
+ class->cmp_fn(prev->instance, next->instance) < 0)
+ continue;
+
/*
* We're holding the nest_lock, which serializes this lock's
* nesting behaviour.
@@ -3085,6 +3105,14 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
return 2;
}
+ if (prev->class_idx == next->class_idx) {
+ struct lock_class *class = hlock_class(prev);
+
+ if (class->cmp_fn &&
+ class->cmp_fn(prev->instance, next->instance) < 0)
+ return 2;
+ }
+
/*
* Prove that the new <prev> -> <next> dependency would not
* create a circular dependency in the graph. (We do this by
@@ -3918,11 +3946,11 @@ static void print_usage_bug_scenario(struct held_lock *lock)
printk(" CPU0\n");
printk(" ----\n");
printk(" lock(");
- __print_lock_name(class);
+ __print_lock_name(lock, class);
printk(KERN_CONT ");\n");
printk(" <Interrupt>\n");
printk(" lock(");
- __print_lock_name(class);
+ __print_lock_name(lock, class);
printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
}
@@ -4008,7 +4036,7 @@ print_irq_inversion_bug(struct task_struct *curr,
pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
else
pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
- print_lock_name(other->class);
+ print_lock_name(NULL, other->class);
pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
pr_warn("\nother info that might help us debug this:\n");
@@ -4866,6 +4894,33 @@ EXPORT_SYMBOL_GPL(lockdep_init_map_type);
struct lock_class_key __lockdep_no_validate__;
EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
+#ifdef CONFIG_PROVE_LOCKING
+void lockdep_set_lock_cmp_fn(struct lockdep_map *lock, lock_cmp_fn cmp_fn,
+ lock_print_fn print_fn)
+{
+ struct lock_class *class = lock->class_cache[0];
+ unsigned long flags;
+
+ raw_local_irq_save(flags);
+ lockdep_recursion_inc();
+
+ if (!class)
+ class = register_lock_class(lock, 0, 0);
+
+ if (class) {
+ WARN_ON(class->cmp_fn && class->cmp_fn != cmp_fn);
+ WARN_ON(class->print_fn && class->print_fn != print_fn);
+
+ class->cmp_fn = cmp_fn;
+ class->print_fn = print_fn;
+ }
+
+ lockdep_recursion_finish();
+ raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lockdep_set_lock_cmp_fn);
+#endif
+
static void
print_lock_nested_lock_not_held(struct task_struct *curr,
struct held_lock *hlock)
--
2.40.1
Hi Kent,
kernel test robot noticed the following build warnings:
[auto build test WARNING on tip/locking/core]
[cannot apply to linus/master v6.4-rc1 next-20230509]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Kent-Overstreet/bcache-Convert-to-lock_cmp_fn/20230510-040030
base: tip/locking/core
patch link: https://lore.kernel.org/r/20230509195847.1745548-1-kent.overstreet%40linux.dev
patch subject: [PATCH 1/2] lockdep: lock_set_cmp_fn()
config: loongarch-allyesconfig (https://download.01.org/0day-ci/archive/20230510/[email protected]/config)
compiler: loongarch64-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/f265373c48cadb6f81e032df9893abffc370ab89
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Kent-Overstreet/bcache-Convert-to-lock_cmp_fn/20230510-040030
git checkout f265373c48cadb6f81e032df9893abffc370ab89
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=loongarch olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=loongarch SHELL=/bin/bash drivers/md/bcache/ kernel/locking/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>
| Link: https://lore.kernel.org/oe-kbuild-all/[email protected]/
All warnings (new ones prefixed by >>):
kernel/locking/lockdep.c: In function 'print_chain_keys_chain':
kernel/locking/lockdep.c:3592:46: error: passing argument 1 of 'print_lock_name' from incompatible pointer type [-Werror=incompatible-pointer-types]
3592 | print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id));
| ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| |
| struct lock_class *
kernel/locking/lockdep.c:732:47: note: expected 'struct held_lock *' but argument is of type 'struct lock_class *'
732 | static void print_lock_name(struct held_lock *hlock, struct lock_class *class)
| ~~~~~~~~~~~~~~~~~~^~~~~
kernel/locking/lockdep.c:3592:17: error: too few arguments to function 'print_lock_name'
3592 | print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id));
| ^~~~~~~~~~~~~~~
kernel/locking/lockdep.c:732:13: note: declared here
732 | static void print_lock_name(struct held_lock *hlock, struct lock_class *class)
| ^~~~~~~~~~~~~~~
kernel/locking/lockdep.c: At top level:
>> kernel/locking/lockdep.c:4898:6: warning: no previous prototype for 'lockdep_set_lock_cmp_fn' [-Wmissing-prototypes]
4898 | void lockdep_set_lock_cmp_fn(struct lockdep_map *lock, lock_cmp_fn cmp_fn,
| ^~~~~~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors
vim +/lockdep_set_lock_cmp_fn +4898 kernel/locking/lockdep.c
4896
4897 #ifdef CONFIG_PROVE_LOCKING
> 4898 void lockdep_set_lock_cmp_fn(struct lockdep_map *lock, lock_cmp_fn cmp_fn,
4899 lock_print_fn print_fn)
4900 {
4901 struct lock_class *class = lock->class_cache[0];
4902 unsigned long flags;
4903
4904 raw_local_irq_save(flags);
4905 lockdep_recursion_inc();
4906
4907 if (!class)
4908 class = register_lock_class(lock, 0, 0);
4909
4910 if (class) {
4911 WARN_ON(class->cmp_fn && class->cmp_fn != cmp_fn);
4912 WARN_ON(class->print_fn && class->print_fn != print_fn);
4913
4914 class->cmp_fn = cmp_fn;
4915 class->print_fn = print_fn;
4916 }
4917
4918 lockdep_recursion_finish();
4919 raw_local_irq_restore(flags);
4920 }
4921 EXPORT_SYMBOL_GPL(lockdep_set_lock_cmp_fn);
4922 #endif
4923
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests
Hi Kent,
kernel test robot noticed the following build errors:
[auto build test ERROR on tip/locking/core]
[cannot apply to linus/master v6.4-rc1 next-20230509]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Kent-Overstreet/bcache-Convert-to-lock_cmp_fn/20230510-040030
base: tip/locking/core
patch link: https://lore.kernel.org/r/20230509195847.1745548-1-kent.overstreet%40linux.dev
patch subject: [PATCH 1/2] lockdep: lock_set_cmp_fn()
config: loongarch-allyesconfig (https://download.01.org/0day-ci/archive/20230510/[email protected]/config)
compiler: loongarch64-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/f265373c48cadb6f81e032df9893abffc370ab89
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Kent-Overstreet/bcache-Convert-to-lock_cmp_fn/20230510-040030
git checkout f265373c48cadb6f81e032df9893abffc370ab89
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=loongarch olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=loongarch SHELL=/bin/bash drivers/md/ kernel/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>
| Link: https://lore.kernel.org/oe-kbuild-all/[email protected]/
All errors (new ones prefixed by >>):
kernel/locking/lockdep.c: In function 'print_chain_keys_chain':
>> kernel/locking/lockdep.c:3592:46: error: passing argument 1 of 'print_lock_name' from incompatible pointer type [-Werror=incompatible-pointer-types]
3592 | print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id));
| ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| |
| struct lock_class *
kernel/locking/lockdep.c:732:47: note: expected 'struct held_lock *' but argument is of type 'struct lock_class *'
732 | static void print_lock_name(struct held_lock *hlock, struct lock_class *class)
| ~~~~~~~~~~~~~~~~~~^~~~~
>> kernel/locking/lockdep.c:3592:17: error: too few arguments to function 'print_lock_name'
3592 | print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id));
| ^~~~~~~~~~~~~~~
kernel/locking/lockdep.c:732:13: note: declared here
732 | static void print_lock_name(struct held_lock *hlock, struct lock_class *class)
| ^~~~~~~~~~~~~~~
kernel/locking/lockdep.c: At top level:
kernel/locking/lockdep.c:4898:6: warning: no previous prototype for 'lockdep_set_lock_cmp_fn' [-Wmissing-prototypes]
4898 | void lockdep_set_lock_cmp_fn(struct lockdep_map *lock, lock_cmp_fn cmp_fn,
| ^~~~~~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors
vim +/print_lock_name +3592 kernel/locking/lockdep.c
39e2e173fb1f90 Alfredo Alvarez Fernandez 2016-03-30 3580
39e2e173fb1f90 Alfredo Alvarez Fernandez 2016-03-30 3581 static void print_chain_keys_chain(struct lock_chain *chain)
39e2e173fb1f90 Alfredo Alvarez Fernandez 2016-03-30 3582 {
39e2e173fb1f90 Alfredo Alvarez Fernandez 2016-03-30 3583 int i;
f6ec8829ac9d59 Yuyang Du 2019-05-06 3584 u64 chain_key = INITIAL_CHAIN_KEY;
f611e8cf98ec90 Boqun Feng 2020-08-07 3585 u16 hlock_id;
39e2e173fb1f90 Alfredo Alvarez Fernandez 2016-03-30 3586
39e2e173fb1f90 Alfredo Alvarez Fernandez 2016-03-30 3587 printk("depth: %u\n", chain->depth);
39e2e173fb1f90 Alfredo Alvarez Fernandez 2016-03-30 3588 for (i = 0; i < chain->depth; i++) {
f611e8cf98ec90 Boqun Feng 2020-08-07 3589 hlock_id = chain_hlocks[chain->base + i];
f611e8cf98ec90 Boqun Feng 2020-08-07 3590 chain_key = print_chain_key_iteration(hlock_id, chain_key);
39e2e173fb1f90 Alfredo Alvarez Fernandez 2016-03-30 3591
28df029d53a2fd Cheng Jui Wang 2022-02-10 @3592 print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id));
39e2e173fb1f90 Alfredo Alvarez Fernandez 2016-03-30 3593 printk("\n");
39e2e173fb1f90 Alfredo Alvarez Fernandez 2016-03-30 3594 }
39e2e173fb1f90 Alfredo Alvarez Fernandez 2016-03-30 3595 }
39e2e173fb1f90 Alfredo Alvarez Fernandez 2016-03-30 3596
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests
The following commit has been merged into the locking/core branch of tip:
Commit-ID: eb1cfd09f788e39948a82be8063e54e40dd018d9
Gitweb: https://git.kernel.org/tip/eb1cfd09f788e39948a82be8063e54e40dd018d9
Author: Kent Overstreet <[email protected]>
AuthorDate: Tue, 09 May 2023 15:58:46 -04:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Fri, 19 May 2023 12:35:10 +02:00
lockdep: Add lock_set_cmp_fn() annotation
This implements a new interface to lockdep, lock_set_cmp_fn(), for
defining a custom ordering when taking multiple locks of the same
class.
This is an alternative to subclasses, but can not fully replace them
since subclasses allow lock hierarchies with other clasees
inter-twined, while this relies on pure class nesting.
Specifically, if A is our nesting class then:
A/0 <- B <- A/1
Would be a valid lock order with subclasses (each subclass really is a
full class from the validation PoV) but not with this annotation,
which requires all nesting to be consecutive.
Example output:
| ============================================
| WARNING: possible recursive locking detected
| 6.2.0-rc8-00003-g7d81e591ca6a-dirty #15 Not tainted
| --------------------------------------------
| kworker/14:3/938 is trying to acquire lock:
| ffff8880143218c8 (&b->lock l=0 0:2803368){++++}-{3:3}, at: bch_btree_node_get.part.0+0x81/0x2b0
|
| but task is already holding lock:
| ffff8880143de8c8 (&b->lock l=1 1048575:9223372036854775807){++++}-{3:3}, at: __bch_btree_map_nodes+0xea/0x1e0
| and the lock comparison function returns 1:
|
| other info that might help us debug this:
| Possible unsafe locking scenario:
|
| CPU0
| ----
| lock(&b->lock l=1 1048575:9223372036854775807);
| lock(&b->lock l=0 0:2803368);
|
| *** DEADLOCK ***
|
| May be due to missing lock nesting notation
|
| 3 locks held by kworker/14:3/938:
| #0: ffff888005ea9d38 ((wq_completion)bcache){+.+.}-{0:0}, at: process_one_work+0x1ec/0x530
| #1: ffff8880098c3e70 ((work_completion)(&cl->work)#3){+.+.}-{0:0}, at: process_one_work+0x1ec/0x530
| #2: ffff8880143de8c8 (&b->lock l=1 1048575:9223372036854775807){++++}-{3:3}, at: __bch_btree_map_nodes+0xea/0x1e0
[peterz: extended changelog]
Signed-off-by: Kent Overstreet <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
---
include/linux/lockdep.h | 8 ++-
include/linux/lockdep_types.h | 8 ++-
kernel/locking/lockdep.c | 118 ++++++++++++++++++++++++---------
3 files changed, 103 insertions(+), 31 deletions(-)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index b32256e..3bac150 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -434,6 +434,14 @@ extern int lockdep_is_held(const void *);
#endif /* !LOCKDEP */
+#ifdef CONFIG_PROVE_LOCKING
+void lockdep_set_lock_cmp_fn(struct lockdep_map *, lock_cmp_fn, lock_print_fn);
+
+#define lock_set_cmp_fn(lock, ...) lockdep_set_lock_cmp_fn(&(lock)->dep_map, __VA_ARGS__)
+#else
+#define lock_set_cmp_fn(lock, ...) do { } while (0)
+#endif
+
enum xhlock_context_t {
XHLOCK_HARD,
XHLOCK_SOFT,
diff --git a/include/linux/lockdep_types.h b/include/linux/lockdep_types.h
index d224308..8bf79c4 100644
--- a/include/linux/lockdep_types.h
+++ b/include/linux/lockdep_types.h
@@ -84,6 +84,11 @@ struct lock_trace;
#define LOCKSTAT_POINTS 4
+struct lockdep_map;
+typedef int (*lock_cmp_fn)(const struct lockdep_map *a,
+ const struct lockdep_map *b);
+typedef void (*lock_print_fn)(const struct lockdep_map *map);
+
/*
* The lock-class itself. The order of the structure members matters.
* reinit_class() zeroes the key member and all subsequent members.
@@ -109,6 +114,9 @@ struct lock_class {
struct list_head locks_after, locks_before;
const struct lockdep_subclass_key *key;
+ lock_cmp_fn cmp_fn;
+ lock_print_fn print_fn;
+
unsigned int subclass;
unsigned int dep_gen_id;
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index dcd1d5b..3e8950f 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -709,7 +709,7 @@ void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
usage[i] = '\0';
}
-static void __print_lock_name(struct lock_class *class)
+static void __print_lock_name(struct held_lock *hlock, struct lock_class *class)
{
char str[KSYM_NAME_LEN];
const char *name;
@@ -724,17 +724,19 @@ static void __print_lock_name(struct lock_class *class)
printk(KERN_CONT "#%d", class->name_version);
if (class->subclass)
printk(KERN_CONT "/%d", class->subclass);
+ if (hlock && class->print_fn)
+ class->print_fn(hlock->instance);
}
}
-static void print_lock_name(struct lock_class *class)
+static void print_lock_name(struct held_lock *hlock, struct lock_class *class)
{
char usage[LOCK_USAGE_CHARS];
get_usage_chars(class, usage);
printk(KERN_CONT " (");
- __print_lock_name(class);
+ __print_lock_name(hlock, class);
printk(KERN_CONT "){%s}-{%d:%d}", usage,
class->wait_type_outer ?: class->wait_type_inner,
class->wait_type_inner);
@@ -772,7 +774,7 @@ static void print_lock(struct held_lock *hlock)
}
printk(KERN_CONT "%px", hlock->instance);
- print_lock_name(lock);
+ print_lock_name(hlock, lock);
printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
}
@@ -1868,7 +1870,7 @@ print_circular_bug_entry(struct lock_list *target, int depth)
if (debug_locks_silent)
return;
printk("\n-> #%u", depth);
- print_lock_name(target->class);
+ print_lock_name(NULL, target->class);
printk(KERN_CONT ":\n");
print_lock_trace(target->trace, 6);
}
@@ -1899,11 +1901,11 @@ print_circular_lock_scenario(struct held_lock *src,
*/
if (parent != source) {
printk("Chain exists of:\n ");
- __print_lock_name(source);
+ __print_lock_name(src, source);
printk(KERN_CONT " --> ");
- __print_lock_name(parent);
+ __print_lock_name(NULL, parent);
printk(KERN_CONT " --> ");
- __print_lock_name(target);
+ __print_lock_name(tgt, target);
printk(KERN_CONT "\n\n");
}
@@ -1914,13 +1916,13 @@ print_circular_lock_scenario(struct held_lock *src,
printk(" rlock(");
else
printk(" lock(");
- __print_lock_name(target);
+ __print_lock_name(tgt, target);
printk(KERN_CONT ");\n");
printk(" lock(");
- __print_lock_name(parent);
+ __print_lock_name(NULL, parent);
printk(KERN_CONT ");\n");
printk(" lock(");
- __print_lock_name(target);
+ __print_lock_name(tgt, target);
printk(KERN_CONT ");\n");
if (src_read != 0)
printk(" rlock(");
@@ -1928,7 +1930,7 @@ print_circular_lock_scenario(struct held_lock *src,
printk(" sync(");
else
printk(" lock(");
- __print_lock_name(source);
+ __print_lock_name(src, source);
printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
}
@@ -2154,6 +2156,8 @@ check_path(struct held_lock *target, struct lock_list *src_entry,
return ret;
}
+static void print_deadlock_bug(struct task_struct *, struct held_lock *, struct held_lock *);
+
/*
* Prove that the dependency graph starting at <src> can not
* lead to <target>. If it can, there is a circle when adding
@@ -2185,7 +2189,10 @@ check_noncircular(struct held_lock *src, struct held_lock *target,
*trace = save_trace();
}
- print_circular_bug(&src_entry, target_entry, src, target);
+ if (src->class_idx == target->class_idx)
+ print_deadlock_bug(current, src, target);
+ else
+ print_circular_bug(&src_entry, target_entry, src, target);
}
return ret;
@@ -2341,7 +2348,7 @@ static void print_lock_class_header(struct lock_class *class, int depth)
int bit;
printk("%*s->", depth, "");
- print_lock_name(class);
+ print_lock_name(NULL, class);
#ifdef CONFIG_DEBUG_LOCKDEP
printk(KERN_CONT " ops: %lu", debug_class_ops_read(class));
#endif
@@ -2523,11 +2530,11 @@ print_irq_lock_scenario(struct lock_list *safe_entry,
*/
if (middle_class != unsafe_class) {
printk("Chain exists of:\n ");
- __print_lock_name(safe_class);
+ __print_lock_name(NULL, safe_class);
printk(KERN_CONT " --> ");
- __print_lock_name(middle_class);
+ __print_lock_name(NULL, middle_class);
printk(KERN_CONT " --> ");
- __print_lock_name(unsafe_class);
+ __print_lock_name(NULL, unsafe_class);
printk(KERN_CONT "\n\n");
}
@@ -2535,18 +2542,18 @@ print_irq_lock_scenario(struct lock_list *safe_entry,
printk(" CPU0 CPU1\n");
printk(" ---- ----\n");
printk(" lock(");
- __print_lock_name(unsafe_class);
+ __print_lock_name(NULL, unsafe_class);
printk(KERN_CONT ");\n");
printk(" local_irq_disable();\n");
printk(" lock(");
- __print_lock_name(safe_class);
+ __print_lock_name(NULL, safe_class);
printk(KERN_CONT ");\n");
printk(" lock(");
- __print_lock_name(middle_class);
+ __print_lock_name(NULL, middle_class);
printk(KERN_CONT ");\n");
printk(" <Interrupt>\n");
printk(" lock(");
- __print_lock_name(safe_class);
+ __print_lock_name(NULL, safe_class);
printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
}
@@ -2583,20 +2590,20 @@ print_bad_irq_dependency(struct task_struct *curr,
pr_warn("\nand this task is already holding:\n");
print_lock(prev);
pr_warn("which would create a new lock dependency:\n");
- print_lock_name(hlock_class(prev));
+ print_lock_name(prev, hlock_class(prev));
pr_cont(" ->");
- print_lock_name(hlock_class(next));
+ print_lock_name(next, hlock_class(next));
pr_cont("\n");
pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
irqclass);
- print_lock_name(backwards_entry->class);
+ print_lock_name(NULL, backwards_entry->class);
pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
print_lock_trace(backwards_entry->class->usage_traces[bit1], 1);
pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
- print_lock_name(forwards_entry->class);
+ print_lock_name(NULL, forwards_entry->class);
pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
pr_warn("...");
@@ -2966,10 +2973,10 @@ print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
printk(" CPU0\n");
printk(" ----\n");
printk(" lock(");
- __print_lock_name(prev);
+ __print_lock_name(prv, prev);
printk(KERN_CONT ");\n");
printk(" lock(");
- __print_lock_name(next);
+ __print_lock_name(nxt, next);
printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
printk(" May be due to missing lock nesting notation\n\n");
@@ -2979,6 +2986,8 @@ static void
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
struct held_lock *next)
{
+ struct lock_class *class = hlock_class(prev);
+
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return;
@@ -2993,6 +3002,11 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
pr_warn("\nbut task is already holding lock:\n");
print_lock(prev);
+ if (class->cmp_fn) {
+ pr_warn("and the lock comparison function returns %i:\n",
+ class->cmp_fn(prev->instance, next->instance));
+ }
+
pr_warn("\nother info that might help us debug this:\n");
print_deadlock_scenario(next, prev);
lockdep_print_held_locks(curr);
@@ -3014,6 +3028,7 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
static int
check_deadlock(struct task_struct *curr, struct held_lock *next)
{
+ struct lock_class *class;
struct held_lock *prev;
struct held_lock *nest = NULL;
int i;
@@ -3034,6 +3049,12 @@ check_deadlock(struct task_struct *curr, struct held_lock *next)
if ((next->read == 2) && prev->read)
continue;
+ class = hlock_class(prev);
+
+ if (class->cmp_fn &&
+ class->cmp_fn(prev->instance, next->instance) < 0)
+ continue;
+
/*
* We're holding the nest_lock, which serializes this lock's
* nesting behaviour.
@@ -3095,6 +3116,14 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
return 2;
}
+ if (prev->class_idx == next->class_idx) {
+ struct lock_class *class = hlock_class(prev);
+
+ if (class->cmp_fn &&
+ class->cmp_fn(prev->instance, next->instance) < 0)
+ return 2;
+ }
+
/*
* Prove that the new <prev> -> <next> dependency would not
* create a circular dependency in the graph. (We do this by
@@ -3571,7 +3600,7 @@ static void print_chain_keys_chain(struct lock_chain *chain)
hlock_id = chain_hlocks[chain->base + i];
chain_key = print_chain_key_iteration(hlock_id, chain_key);
- print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id));
+ print_lock_name(NULL, lock_classes + chain_hlock_class_idx(hlock_id));
printk("\n");
}
}
@@ -3928,11 +3957,11 @@ static void print_usage_bug_scenario(struct held_lock *lock)
printk(" CPU0\n");
printk(" ----\n");
printk(" lock(");
- __print_lock_name(class);
+ __print_lock_name(lock, class);
printk(KERN_CONT ");\n");
printk(" <Interrupt>\n");
printk(" lock(");
- __print_lock_name(class);
+ __print_lock_name(lock, class);
printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
}
@@ -4018,7 +4047,7 @@ print_irq_inversion_bug(struct task_struct *curr,
pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
else
pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
- print_lock_name(other->class);
+ print_lock_name(NULL, other->class);
pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
pr_warn("\nother info that might help us debug this:\n");
@@ -4882,6 +4911,33 @@ EXPORT_SYMBOL_GPL(lockdep_init_map_type);
struct lock_class_key __lockdep_no_validate__;
EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
+#ifdef CONFIG_PROVE_LOCKING
+void lockdep_set_lock_cmp_fn(struct lockdep_map *lock, lock_cmp_fn cmp_fn,
+ lock_print_fn print_fn)
+{
+ struct lock_class *class = lock->class_cache[0];
+ unsigned long flags;
+
+ raw_local_irq_save(flags);
+ lockdep_recursion_inc();
+
+ if (!class)
+ class = register_lock_class(lock, 0, 0);
+
+ if (class) {
+ WARN_ON(class->cmp_fn && class->cmp_fn != cmp_fn);
+ WARN_ON(class->print_fn && class->print_fn != print_fn);
+
+ class->cmp_fn = cmp_fn;
+ class->print_fn = print_fn;
+ }
+
+ lockdep_recursion_finish();
+ raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lockdep_set_lock_cmp_fn);
+#endif
+
static void
print_lock_nested_lock_not_held(struct task_struct *curr,
struct held_lock *hlock)