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author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-17 20:58:12 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-17 20:58:12 -0800 |
commit | 848b81415c42ff3dc9a4204749087b015c37ef66 (patch) | |
tree | 391da3a73aea48632248220d2d6b8d45a88f7eae /include/linux/percpu-rwsem.h | |
parent | 992956189de58cae9f2be40585bc25105cd7c5ad (diff) | |
parent | 6fd59a83b9261fa53eaf98fb5514abba504a3ea3 (diff) | |
download | op-kernel-dev-848b81415c42ff3dc9a4204749087b015c37ef66.zip op-kernel-dev-848b81415c42ff3dc9a4204749087b015c37ef66.tar.gz |
Merge branch 'akpm' (Andrew's patch-bomb)
Merge misc patches from Andrew Morton:
"Incoming:
- lots of misc stuff
- backlight tree updates
- lib/ updates
- Oleg's percpu-rwsem changes
- checkpatch
- rtc
- aoe
- more checkpoint/restart support
I still have a pile of MM stuff pending - Pekka should be merging
later today after which that is good to go. A number of other things
are twiddling thumbs awaiting maintainer merges."
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (180 commits)
scatterlist: don't BUG when we can trivially return a proper error.
docs: update documentation about /proc/<pid>/fdinfo/<fd> fanotify output
fs, fanotify: add @mflags field to fanotify output
docs: add documentation about /proc/<pid>/fdinfo/<fd> output
fs, notify: add procfs fdinfo helper
fs, exportfs: add exportfs_encode_inode_fh() helper
fs, exportfs: escape nil dereference if no s_export_op present
fs, epoll: add procfs fdinfo helper
fs, eventfd: add procfs fdinfo helper
procfs: add ability to plug in auxiliary fdinfo providers
tools/testing/selftests/kcmp/kcmp_test.c: print reason for failure in kcmp_test
breakpoint selftests: print failure status instead of cause make error
kcmp selftests: print fail status instead of cause make error
kcmp selftests: make run_tests fix
mem-hotplug selftests: print failure status instead of cause make error
cpu-hotplug selftests: print failure status instead of cause make error
mqueue selftests: print failure status instead of cause make error
vm selftests: print failure status instead of cause make error
ubifs: use prandom_bytes
mtd: nandsim: use prandom_bytes
...
Diffstat (limited to 'include/linux/percpu-rwsem.h')
-rw-r--r-- | include/linux/percpu-rwsem.h | 91 |
1 files changed, 21 insertions, 70 deletions
diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h index bd1e860..3e88c9a 100644 --- a/include/linux/percpu-rwsem.h +++ b/include/linux/percpu-rwsem.h @@ -1,83 +1,34 @@ #ifndef _LINUX_PERCPU_RWSEM_H #define _LINUX_PERCPU_RWSEM_H -#include <linux/mutex.h> +#include <linux/atomic.h> +#include <linux/rwsem.h> #include <linux/percpu.h> -#include <linux/rcupdate.h> -#include <linux/delay.h> +#include <linux/wait.h> +#include <linux/lockdep.h> struct percpu_rw_semaphore { - unsigned __percpu *counters; - bool locked; - struct mutex mtx; + unsigned int __percpu *fast_read_ctr; + atomic_t write_ctr; + struct rw_semaphore rw_sem; + atomic_t slow_read_ctr; + wait_queue_head_t write_waitq; }; -#define light_mb() barrier() -#define heavy_mb() synchronize_sched_expedited() +extern void percpu_down_read(struct percpu_rw_semaphore *); +extern void percpu_up_read(struct percpu_rw_semaphore *); -static inline void percpu_down_read(struct percpu_rw_semaphore *p) -{ - rcu_read_lock_sched(); - if (unlikely(p->locked)) { - rcu_read_unlock_sched(); - mutex_lock(&p->mtx); - this_cpu_inc(*p->counters); - mutex_unlock(&p->mtx); - return; - } - this_cpu_inc(*p->counters); - rcu_read_unlock_sched(); - light_mb(); /* A, between read of p->locked and read of data, paired with D */ -} +extern void percpu_down_write(struct percpu_rw_semaphore *); +extern void percpu_up_write(struct percpu_rw_semaphore *); -static inline void percpu_up_read(struct percpu_rw_semaphore *p) -{ - light_mb(); /* B, between read of the data and write to p->counter, paired with C */ - this_cpu_dec(*p->counters); -} +extern int __percpu_init_rwsem(struct percpu_rw_semaphore *, + const char *, struct lock_class_key *); +extern void percpu_free_rwsem(struct percpu_rw_semaphore *); -static inline unsigned __percpu_count(unsigned __percpu *counters) -{ - unsigned total = 0; - int cpu; - - for_each_possible_cpu(cpu) - total += ACCESS_ONCE(*per_cpu_ptr(counters, cpu)); - - return total; -} - -static inline void percpu_down_write(struct percpu_rw_semaphore *p) -{ - mutex_lock(&p->mtx); - p->locked = true; - synchronize_sched_expedited(); /* make sure that all readers exit the rcu_read_lock_sched region */ - while (__percpu_count(p->counters)) - msleep(1); - heavy_mb(); /* C, between read of p->counter and write to data, paired with B */ -} - -static inline void percpu_up_write(struct percpu_rw_semaphore *p) -{ - heavy_mb(); /* D, between write to data and write to p->locked, paired with A */ - p->locked = false; - mutex_unlock(&p->mtx); -} - -static inline int percpu_init_rwsem(struct percpu_rw_semaphore *p) -{ - p->counters = alloc_percpu(unsigned); - if (unlikely(!p->counters)) - return -ENOMEM; - p->locked = false; - mutex_init(&p->mtx); - return 0; -} - -static inline void percpu_free_rwsem(struct percpu_rw_semaphore *p) -{ - free_percpu(p->counters); - p->counters = NULL; /* catch use after free bugs */ -} +#define percpu_init_rwsem(brw) \ +({ \ + static struct lock_class_key rwsem_key; \ + __percpu_init_rwsem(brw, #brw, &rwsem_key); \ +}) #endif |