diff options
Diffstat (limited to '')
| -rw-r--r-- | debian/patches-rt/0169-locking-percpu-rwsem-Remove-preempt_disable-variants.patch | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/debian/patches-rt/0169-locking-percpu-rwsem-Remove-preempt_disable-variants.patch b/debian/patches-rt/0169-locking-percpu-rwsem-Remove-preempt_disable-variants.patch new file mode 100644 index 000000000..a6a0cd7c4 --- /dev/null +++ b/debian/patches-rt/0169-locking-percpu-rwsem-Remove-preempt_disable-variants.patch @@ -0,0 +1,226 @@ +From 80adc8fb1dabebcc9d41cb6c0f122860061c12a3 Mon Sep 17 00:00:00 2001 +From: Peter Zijlstra <peterz@infradead.org> +Date: Wed, 23 Nov 2016 16:29:32 +0100 +Subject: [PATCH 169/347] locking/percpu-rwsem: Remove preempt_disable variants +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz + +Effective revert commit: + + 87709e28dc7c ("fs/locks: Use percpu_down_read_preempt_disable()") + +This is causing major pain for PREEMPT_RT and is only a very small +performance issue for PREEMPT=y. + +Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> +--- + fs/locks.c | 32 ++++++++++++++++---------------- + include/linux/percpu-rwsem.h | 24 ++++-------------------- + 2 files changed, 20 insertions(+), 36 deletions(-) + +diff --git a/fs/locks.c b/fs/locks.c +index 28270e74be34..552476d6f6bb 100644 +--- a/fs/locks.c ++++ b/fs/locks.c +@@ -936,7 +936,7 @@ static int flock_lock_inode(struct inode *inode, struct file_lock *request) + return -ENOMEM; + } + +- percpu_down_read_preempt_disable(&file_rwsem); ++ percpu_down_read(&file_rwsem); + spin_lock(&ctx->flc_lock); + if (request->fl_flags & FL_ACCESS) + goto find_conflict; +@@ -977,7 +977,7 @@ static int flock_lock_inode(struct inode *inode, struct file_lock *request) + + out: + spin_unlock(&ctx->flc_lock); +- percpu_up_read_preempt_enable(&file_rwsem); ++ percpu_up_read(&file_rwsem); + if (new_fl) + locks_free_lock(new_fl); + locks_dispose_list(&dispose); +@@ -1015,7 +1015,7 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request, + new_fl2 = locks_alloc_lock(); + } + +- percpu_down_read_preempt_disable(&file_rwsem); ++ percpu_down_read(&file_rwsem); + spin_lock(&ctx->flc_lock); + /* + * New lock request. Walk all POSIX locks and look for conflicts. If +@@ -1187,7 +1187,7 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request, + } + out: + spin_unlock(&ctx->flc_lock); +- percpu_up_read_preempt_enable(&file_rwsem); ++ percpu_up_read(&file_rwsem); + /* + * Free any unused locks. + */ +@@ -1462,7 +1462,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type) + return error; + } + +- percpu_down_read_preempt_disable(&file_rwsem); ++ percpu_down_read(&file_rwsem); + spin_lock(&ctx->flc_lock); + + time_out_leases(inode, &dispose); +@@ -1514,13 +1514,13 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type) + locks_insert_block(fl, new_fl); + trace_break_lease_block(inode, new_fl); + spin_unlock(&ctx->flc_lock); +- percpu_up_read_preempt_enable(&file_rwsem); ++ percpu_up_read(&file_rwsem); + + locks_dispose_list(&dispose); + error = wait_event_interruptible_timeout(new_fl->fl_wait, + !new_fl->fl_next, break_time); + +- percpu_down_read_preempt_disable(&file_rwsem); ++ percpu_down_read(&file_rwsem); + spin_lock(&ctx->flc_lock); + trace_break_lease_unblock(inode, new_fl); + locks_delete_block(new_fl); +@@ -1537,7 +1537,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type) + } + out: + spin_unlock(&ctx->flc_lock); +- percpu_up_read_preempt_enable(&file_rwsem); ++ percpu_up_read(&file_rwsem); + locks_dispose_list(&dispose); + locks_free_lock(new_fl); + return error; +@@ -1609,7 +1609,7 @@ int fcntl_getlease(struct file *filp) + + ctx = smp_load_acquire(&inode->i_flctx); + if (ctx && !list_empty_careful(&ctx->flc_lease)) { +- percpu_down_read_preempt_disable(&file_rwsem); ++ percpu_down_read(&file_rwsem); + spin_lock(&ctx->flc_lock); + time_out_leases(inode, &dispose); + list_for_each_entry(fl, &ctx->flc_lease, fl_list) { +@@ -1619,7 +1619,7 @@ int fcntl_getlease(struct file *filp) + break; + } + spin_unlock(&ctx->flc_lock); +- percpu_up_read_preempt_enable(&file_rwsem); ++ percpu_up_read(&file_rwsem); + + locks_dispose_list(&dispose); + } +@@ -1693,7 +1693,7 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr + return -EINVAL; + } + +- percpu_down_read_preempt_disable(&file_rwsem); ++ percpu_down_read(&file_rwsem); + spin_lock(&ctx->flc_lock); + time_out_leases(inode, &dispose); + error = check_conflicting_open(dentry, arg, lease->fl_flags); +@@ -1764,7 +1764,7 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr + lease->fl_lmops->lm_setup(lease, priv); + out: + spin_unlock(&ctx->flc_lock); +- percpu_up_read_preempt_enable(&file_rwsem); ++ percpu_up_read(&file_rwsem); + locks_dispose_list(&dispose); + if (is_deleg) + inode_unlock(inode); +@@ -1787,7 +1787,7 @@ static int generic_delete_lease(struct file *filp, void *owner) + return error; + } + +- percpu_down_read_preempt_disable(&file_rwsem); ++ percpu_down_read(&file_rwsem); + spin_lock(&ctx->flc_lock); + list_for_each_entry(fl, &ctx->flc_lease, fl_list) { + if (fl->fl_file == filp && +@@ -1800,7 +1800,7 @@ static int generic_delete_lease(struct file *filp, void *owner) + if (victim) + error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose); + spin_unlock(&ctx->flc_lock); +- percpu_up_read_preempt_enable(&file_rwsem); ++ percpu_up_read(&file_rwsem); + locks_dispose_list(&dispose); + return error; + } +@@ -2531,13 +2531,13 @@ locks_remove_lease(struct file *filp, struct file_lock_context *ctx) + if (list_empty(&ctx->flc_lease)) + return; + +- percpu_down_read_preempt_disable(&file_rwsem); ++ percpu_down_read(&file_rwsem); + spin_lock(&ctx->flc_lock); + list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) + if (filp == fl->fl_file) + lease_modify(fl, F_UNLCK, &dispose); + spin_unlock(&ctx->flc_lock); +- percpu_up_read_preempt_enable(&file_rwsem); ++ percpu_up_read(&file_rwsem); + + locks_dispose_list(&dispose); + } +diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h +index 79b99d653e03..fb44e237316d 100644 +--- a/include/linux/percpu-rwsem.h ++++ b/include/linux/percpu-rwsem.h +@@ -29,7 +29,7 @@ static struct percpu_rw_semaphore name = { \ + extern int __percpu_down_read(struct percpu_rw_semaphore *, int); + extern void __percpu_up_read(struct percpu_rw_semaphore *); + +-static inline void percpu_down_read_preempt_disable(struct percpu_rw_semaphore *sem) ++static inline void percpu_down_read(struct percpu_rw_semaphore *sem) + { + might_sleep(); + +@@ -47,16 +47,10 @@ static inline void percpu_down_read_preempt_disable(struct percpu_rw_semaphore * + __this_cpu_inc(*sem->read_count); + if (unlikely(!rcu_sync_is_idle(&sem->rss))) + __percpu_down_read(sem, false); /* Unconditional memory barrier */ +- barrier(); + /* +- * The barrier() prevents the compiler from ++ * The preempt_enable() prevents the compiler from + * bleeding the critical section out. + */ +-} +- +-static inline void percpu_down_read(struct percpu_rw_semaphore *sem) +-{ +- percpu_down_read_preempt_disable(sem); + preempt_enable(); + } + +@@ -83,13 +77,9 @@ static inline int percpu_down_read_trylock(struct percpu_rw_semaphore *sem) + return ret; + } + +-static inline void percpu_up_read_preempt_enable(struct percpu_rw_semaphore *sem) ++static inline void percpu_up_read(struct percpu_rw_semaphore *sem) + { +- /* +- * The barrier() prevents the compiler from +- * bleeding the critical section out. +- */ +- barrier(); ++ preempt_disable(); + /* + * Same as in percpu_down_read(). + */ +@@ -102,12 +92,6 @@ static inline void percpu_up_read_preempt_enable(struct percpu_rw_semaphore *sem + rwsem_release(&sem->rw_sem.dep_map, 1, _RET_IP_); + } + +-static inline void percpu_up_read(struct percpu_rw_semaphore *sem) +-{ +- preempt_disable(); +- percpu_up_read_preempt_enable(sem); +-} +- + extern void percpu_down_write(struct percpu_rw_semaphore *); + extern void percpu_up_write(struct percpu_rw_semaphore *); + +-- +2.36.1 + |