Use spinlock in pipe_read/write cost too much time,IMO
pipe->{head,tail} can be protected by __pipe_{lock,unlock}.
On the other hand, we can use __pipe_{lock,unlock} to protect
the pipe->{head,tail} in pipe_resize_ring and
post_one_notification.
Signed-off-by: Hongchen Zhang <[email protected]>
---
fs/pipe.c | 24 ++++--------------------
include/linux/pipe_fs_i.h | 10 ++++++++++
kernel/watch_queue.c | 8 ++++----
3 files changed, 18 insertions(+), 24 deletions(-)
diff --git a/fs/pipe.c b/fs/pipe.c
index 42c7ff41c2db..cf449779bf71 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -98,16 +98,6 @@ void pipe_unlock(struct pipe_inode_info *pipe)
}
EXPORT_SYMBOL(pipe_unlock);
-static inline void __pipe_lock(struct pipe_inode_info *pipe)
-{
- mutex_lock_nested(&pipe->mutex, I_MUTEX_PARENT);
-}
-
-static inline void __pipe_unlock(struct pipe_inode_info *pipe)
-{
- mutex_unlock(&pipe->mutex);
-}
-
void pipe_double_lock(struct pipe_inode_info *pipe1,
struct pipe_inode_info *pipe2)
{
@@ -253,8 +243,7 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to)
*/
was_full = pipe_full(pipe->head, pipe->tail, pipe->max_usage);
for (;;) {
- /* Read ->head with a barrier vs post_one_notification() */
- unsigned int head = smp_load_acquire(&pipe->head);
+ unsigned int head = pipe->head;
unsigned int tail = pipe->tail;
unsigned int mask = pipe->ring_size - 1;
@@ -322,14 +311,12 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to)
if (!buf->len) {
pipe_buf_release(pipe, buf);
- spin_lock_irq(&pipe->rd_wait.lock);
#ifdef CONFIG_WATCH_QUEUE
if (buf->flags & PIPE_BUF_FLAG_LOSS)
pipe->note_loss = true;
#endif
tail++;
pipe->tail = tail;
- spin_unlock_irq(&pipe->rd_wait.lock);
}
total_len -= chars;
if (!total_len)
@@ -506,16 +493,13 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
* it, either the reader will consume it or it'll still
* be there for the next write.
*/
- spin_lock_irq(&pipe->rd_wait.lock);
head = pipe->head;
if (pipe_full(head, pipe->tail, pipe->max_usage)) {
- spin_unlock_irq(&pipe->rd_wait.lock);
continue;
}
pipe->head = head + 1;
- spin_unlock_irq(&pipe->rd_wait.lock);
/* Insert it into the buffer array */
buf = &pipe->bufs[head & mask];
@@ -1260,14 +1244,14 @@ int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots)
if (unlikely(!bufs))
return -ENOMEM;
- spin_lock_irq(&pipe->rd_wait.lock);
+ __pipe_lock(pipe);
mask = pipe->ring_size - 1;
head = pipe->head;
tail = pipe->tail;
n = pipe_occupancy(head, tail);
if (nr_slots < n) {
- spin_unlock_irq(&pipe->rd_wait.lock);
+ __pipe_unlock(pipe);
kfree(bufs);
return -EBUSY;
}
@@ -1303,7 +1287,7 @@ int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots)
pipe->tail = tail;
pipe->head = head;
- spin_unlock_irq(&pipe->rd_wait.lock);
+ __pipe_unlock(pipe);
/* This might have made more room for writers */
wake_up_interruptible(&pipe->wr_wait);
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 6cb65df3e3ba..baae3d062422 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -223,6 +223,16 @@ static inline void pipe_discard_from(struct pipe_inode_info *pipe,
#define PIPE_SIZE PAGE_SIZE
/* Pipe lock and unlock operations */
+static inline void __pipe_lock(struct pipe_inode_info *pipe)
+{
+ mutex_lock_nested(&pipe->mutex, I_MUTEX_PARENT);
+}
+
+static inline void __pipe_unlock(struct pipe_inode_info *pipe)
+{
+ mutex_unlock(&pipe->mutex);
+}
+
void pipe_lock(struct pipe_inode_info *);
void pipe_unlock(struct pipe_inode_info *);
void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);
diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c
index a6f9bdd956c3..92e46cfe9419 100644
--- a/kernel/watch_queue.c
+++ b/kernel/watch_queue.c
@@ -108,7 +108,7 @@ static bool post_one_notification(struct watch_queue *wqueue,
if (!pipe)
return false;
- spin_lock_irq(&pipe->rd_wait.lock);
+ __pipe_lock(pipe);
mask = pipe->ring_size - 1;
head = pipe->head;
@@ -135,17 +135,17 @@ static bool post_one_notification(struct watch_queue *wqueue,
buf->offset = offset;
buf->len = len;
buf->flags = PIPE_BUF_FLAG_WHOLE;
- smp_store_release(&pipe->head, head + 1); /* vs pipe_read() */
+ pipe->head = head + 1;
if (!test_and_clear_bit(note, wqueue->notes_bitmap)) {
- spin_unlock_irq(&pipe->rd_wait.lock);
+ __pipe_unlock(pipe);
BUG();
}
wake_up_interruptible_sync_poll_locked(&pipe->rd_wait, EPOLLIN | EPOLLRDNORM);
done = true;
out:
- spin_unlock_irq(&pipe->rd_wait.lock);
+ __pipe_unlock(pipe);
if (done)
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
return done;
base-commit: c8451c141e07a8d05693f6c8d0e418fbb4b68bb7
--
2.31.1
Hi Hongchen,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on c8451c141e07a8d05693f6c8d0e418fbb4b68bb7]
url: https://github.com/intel-lab-lkp/linux/commits/Hongchen-Zhang/pipe-use-__pipe_-lock-unlock-instead-of-spinlock/20230103-110504
base: c8451c141e07a8d05693f6c8d0e418fbb4b68bb7
patch link: https://lore.kernel.org/r/20230103030329.20252-1-zhanghongchen%40loongson.cn
patch subject: [PATCH] pipe: use __pipe_{lock,unlock} instead of spinlock
config: x86_64-rhel-8.3-kselftests
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce (this is a W=1 build):
# https://github.com/intel-lab-lkp/linux/commit/74b922b9da7ec76cce2065114d07afc5065b2df9
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Hongchen-Zhang/pipe-use-__pipe_-lock-unlock-instead-of-spinlock/20230103-110504
git checkout 74b922b9da7ec76cce2065114d07afc5065b2df9
# save the config file
mkdir build_dir && cp config build_dir/.config
make W=1 O=build_dir ARCH=x86_64 olddefconfig
make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash net/tls/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>
All errors (new ones prefixed by >>):
In file included from include/linux/splice.h:12,
from net/tls/tls_sw.c:41:
include/linux/pipe_fs_i.h: In function '__pipe_lock':
>> include/linux/pipe_fs_i.h:228:41: error: 'I_MUTEX_PARENT' undeclared (first use in this function)
228 | mutex_lock_nested(&pipe->mutex, I_MUTEX_PARENT);
| ^~~~~~~~~~~~~~
include/linux/pipe_fs_i.h:228:41: note: each undeclared identifier is reported only once for each function it appears in
vim +/I_MUTEX_PARENT +228 include/linux/pipe_fs_i.h
224
225 /* Pipe lock and unlock operations */
226 static inline void __pipe_lock(struct pipe_inode_info *pipe)
227 {
> 228 mutex_lock_nested(&pipe->mutex, I_MUTEX_PARENT);
229 }
230
--
0-DAY CI Kernel Test Service
https://01.org/lkp
Hi Hongchen,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on c8451c141e07a8d05693f6c8d0e418fbb4b68bb7]
url: https://github.com/intel-lab-lkp/linux/commits/Hongchen-Zhang/pipe-use-__pipe_-lock-unlock-instead-of-spinlock/20230103-110504
base: c8451c141e07a8d05693f6c8d0e418fbb4b68bb7
patch link: https://lore.kernel.org/r/20230103030329.20252-1-zhanghongchen%40loongson.cn
patch subject: [PATCH] pipe: use __pipe_{lock,unlock} instead of spinlock
config: sh-allmodconfig
compiler: sh4-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/74b922b9da7ec76cce2065114d07afc5065b2df9
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Hongchen-Zhang/pipe-use-__pipe_-lock-unlock-instead-of-spinlock/20230103-110504
git checkout 74b922b9da7ec76cce2065114d07afc5065b2df9
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=sh olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=sh SHELL=/bin/bash net/tls/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>
All errors (new ones prefixed by >>):
In file included from include/linux/splice.h:12,
from net/tls/tls_sw.c:41:
include/linux/pipe_fs_i.h: In function '__pipe_lock':
>> include/linux/pipe_fs_i.h:228:41: error: 'I_MUTEX_PARENT' undeclared (first use in this function)
228 | mutex_lock_nested(&pipe->mutex, I_MUTEX_PARENT);
| ^~~~~~~~~~~~~~
include/linux/pipe_fs_i.h:228:41: note: each undeclared identifier is reported only once for each function it appears in
vim +/I_MUTEX_PARENT +228 include/linux/pipe_fs_i.h
224
225 /* Pipe lock and unlock operations */
226 static inline void __pipe_lock(struct pipe_inode_info *pipe)
227 {
> 228 mutex_lock_nested(&pipe->mutex, I_MUTEX_PARENT);
229 }
230
--
0-DAY CI Kernel Test Service
https://01.org/lkp