Commit-ID: 916633a403702549d37ea353e63a68e5b0dc27ad
Gitweb: http://git.kernel.org/tip/916633a403702549d37ea353e63a68e5b0dc27ad
Author: Michal Hocko <mhocko@xxxxxxxx>
AuthorDate: Thu, 7 Apr 2016 17:12:31 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 22 Apr 2016 08:58:33 +0200
locking/rwsem: Provide down_write_killable()
Now that all the architectures implement the necessary glue code
we can introduce down_write_killable(). The only difference wrt. regular
down_write() is that the slow path waits in TASK_KILLABLE state and the
interruption by the fatal signal is reported as -EINTR to the caller.
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Chris Zankel <chris@xxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Max Filippov <jcmvbkbc@xxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Signed-off-by: Jason Low <jason.low2@xxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: linux-alpha@xxxxxxxxxxxxxxx
Cc: linux-arch@xxxxxxxxxxxxxxx
Cc: linux-ia64@xxxxxxxxxxxxxxx
Cc: linux-s390@xxxxxxxxxxxxxxx
Cc: linux-sh@xxxxxxxxxxxxxxx
Cc: linux-xtensa@xxxxxxxxxxxxxxxx
Cc: sparclinux@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1460041951-22347-12-git-send-email-mhocko@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/include/asm/rwsem.h | 6 +++---
include/linux/lockdep.h | 15 +++++++++++++++
include/linux/rwsem.h | 1 +
kernel/locking/rwsem.c | 19 +++++++++++++++++++
4 files changed, 38 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h
index d759c5f..453744c 100644
--- a/arch/x86/include/asm/rwsem.h
+++ b/arch/x86/include/asm/rwsem.h
@@ -102,9 +102,9 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
#define ____down_write(sem, slow_path) \
({ \
long tmp; \
- struct rw_semaphore* ret = sem; \
+ struct rw_semaphore* ret; \
asm volatile("# beginning down_write\n\t" \
- LOCK_PREFIX " xadd %1,(%2)\n\t" \
+ LOCK_PREFIX " xadd %1,(%3)\n\t" \
/* adds 0xffff0001, returns the old value */ \
" test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t" \
/* was the active mask 0 before? */\
@@ -112,7 +112,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
" call " slow_path "\n" \
"1:\n" \
"# ending down_write" \
- : "+m" (sem->count), "=d" (tmp), "+a" (ret) \
+ : "+m" (sem->count), "=d" (tmp), "=a" (ret) \
: "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS) \
: "memory", "cc"); \
ret; \
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index d026b19..accfe56 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -444,6 +444,18 @@ do { \
lock_acquired(&(_lock)->dep_map, _RET_IP_); \
} while (0)
+#define LOCK_CONTENDED_RETURN(_lock, try, lock) \
+({ \
+ int ____err = 0; \
+ if (!try(_lock)) { \
+ lock_contended(&(_lock)->dep_map, _RET_IP_); \
+ ____err = lock(_lock); \
+ } \
+ if (!____err) \
+ lock_acquired(&(_lock)->dep_map, _RET_IP_); \
+ ____err; \
+})
+
#else /* CONFIG_LOCK_STAT */
#define lock_contended(lockdep_map, ip) do {} while (0)
@@ -452,6 +464,9 @@ do { \
#define LOCK_CONTENDED(_lock, try, lock) \
lock(_lock)
+#define LOCK_CONTENDED_RETURN(_lock, try, lock) \
+ lock(_lock)
+
#endif /* CONFIG_LOCK_STAT */
#ifdef CONFIG_LOCKDEP
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 7d7ae02..d1c12d1 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -118,6 +118,7 @@ extern int down_read_trylock(struct rw_semaphore *sem);
* lock for writing
*/
extern void down_write(struct rw_semaphore *sem);
+extern int __must_check down_write_killable(struct rw_semaphore *sem);
/*
* trylock for writing -- returns 1 if successful, 0 if contention
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 205be0c..c817216 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -55,6 +55,25 @@ void __sched down_write(struct rw_semaphore *sem)
EXPORT_SYMBOL(down_write);
/*
+ * lock for writing
+ */
+int __sched down_write_killable(struct rw_semaphore *sem)
+{
+ might_sleep();
+ rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
+
+ if (LOCK_CONTENDED_RETURN(sem, __down_write_trylock, __down_write_killable)) {
+ rwsem_release(&sem->dep_map, 1, _RET_IP_);
+ return -EINTR;
+ }
+
+ rwsem_set_owner(sem);
+ return 0;
+}
+
+EXPORT_SYMBOL(down_write_killable);
+
+/*
* trylock for writing -- returns 1 if successful, 0 if contention
*/
int down_write_trylock(struct rw_semaphore *sem)
--
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