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drivers/pipe: Don't use sched_[lock|unlock] to do protection

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since the sched lock can't work in SMP context

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
This commit is contained in:
Xiang Xiao 2022-02-09 02:39:15 +08:00 committed by Petro Karashchenko
parent fe04eb535f
commit e0ae2963d2
1 changed files with 32 additions and 41 deletions
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73
drivers/pipes/pipe_common.c
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@ -216,7 +216,7 @@ int pipecommon_open(FAR struct file *filep)
if (dev->d_nwriters == 1)
{
while (nxsem_get_value(&dev->d_rdsem, &sval) == 0 && sval < 0)
while (nxsem_get_value(&dev->d_rdsem, &sval) == 0 && sval <= 0)
{
nxsem_post(&dev->d_rdsem);
}
@ -232,19 +232,18 @@ int pipecommon_open(FAR struct file *filep)
dev->d_nreaders++;
}
/* If opened for read-only, then wait for either (1) at least one writer
* on the pipe (policy == 0), or (2) until there is buffered data to be
* read (policy == 1).
*/
sched_lock();
nxsem_post(&dev->d_bfsem);
if (!(filep->f_oflags & O_NONBLOCK) && /* Non-blocking */
(filep->f_oflags & O_RDWR) == O_RDONLY && /* Read-only */
dev->d_nwriters < 1 && /* No writers on the pipe */
dev->d_wrndx == dev->d_rdndx) /* Buffer is empty */
while ((filep->f_oflags & O_NONBLOCK) == 0 && /* Non-blocking */
(filep->f_oflags & O_RDWR) == O_RDONLY && /* Read-only */
dev->d_nwriters < 1 && /* No writers on the pipe */
dev->d_wrndx == dev->d_rdndx) /* Buffer is empty */
{
/* If opened for read-only, then wait for either (1) at least one
* writer on the pipe (policy == 0), or (2) until there is buffered
* data to be read (policy == 1).
*/
nxsem_post(&dev->d_bfsem);
/* NOTE: d_rdsem is normally used when the read logic waits for more
* data to be written. But until the first writer has opened the
* pipe, the meaning is different: it is used prevent O_RDONLY open
@ -255,7 +254,7 @@ int pipecommon_open(FAR struct file *filep)
*/
ret = nxsem_wait(&dev->d_rdsem);
if (ret < 0)
if (ret < 0 || (ret = nxsem_wait(&dev->d_bfsem)) < 0)
{
/* The nxsem_wait() call should fail if we are awakened by a
* signal or if the task is canceled.
@ -266,10 +265,11 @@ int pipecommon_open(FAR struct file *filep)
/* Immediately close the pipe that we just opened */
pipecommon_close(filep);
return ret;
}
}
sched_unlock();
nxsem_post(&dev->d_bfsem);
return ret;
}
@ -323,7 +323,7 @@ int pipecommon_close(FAR struct file *filep)
pipecommon_pollnotify(dev, POLLHUP);
while (nxsem_get_value(&dev->d_rdsem, &sval) == 0 && sval < 0)
while (nxsem_get_value(&dev->d_rdsem, &sval) == 0 && sval <= 0)
{
nxsem_post(&dev->d_rdsem);
}
@ -344,7 +344,7 @@ int pipecommon_close(FAR struct file *filep)
pipecommon_pollnotify(dev, POLLERR);
while (nxsem_get_value(&dev->d_wrsem, &sval) == 0
&& sval < 0)
&& sval <= 0)
{
nxsem_post(&dev->d_wrsem);
}
@ -446,10 +446,8 @@ ssize_t pipecommon_read(FAR struct file *filep, FAR char *buffer, size_t len)
/* Otherwise, wait for something to be written to the pipe */
sched_lock();
nxsem_post(&dev->d_bfsem);
ret = nxsem_wait(&dev->d_rdsem);
sched_unlock();
if (ret < 0 || (ret = nxsem_wait(&dev->d_bfsem)) < 0)
{
@ -485,7 +483,7 @@ ssize_t pipecommon_read(FAR struct file *filep, FAR char *buffer, size_t len)
* buffer.
*/
while (nxsem_get_value(&dev->d_wrsem, &sval) == 0 && sval < 0)
while (nxsem_get_value(&dev->d_wrsem, &sval) == 0 && sval <= 0)
{
nxsem_post(&dev->d_wrsem);
}
@ -520,17 +518,6 @@ ssize_t pipecommon_write(FAR struct file *filep, FAR const char *buffer,
return 0;
}
/* REVISIT: "If all file descriptors referring to the read end of a pipe
* have been closed, then a write will cause a SIGPIPE signal to be
* generated for the calling process. If the calling process is ignoring
* this signal, then write(2) fails with the error EPIPE."
*/
if (dev->d_nreaders <= 0)
{
return -EPIPE;
}
/* At present, this method cannot be called from interrupt handlers. That
* is because it calls nxsem_wait() and nxsem_wait() cannot be called from
* interrupt level. This actually happens fairly commonly IF [a-z]err()
@ -563,6 +550,18 @@ ssize_t pipecommon_write(FAR struct file *filep, FAR const char *buffer,
last = 0;
for (; ; )
{
/* REVISIT: "If all file descriptors referring to the read end of a
* pipe have been closed, then a write will cause a SIGPIPE signal to
* be generated for the calling process. If the calling process is
* ignoring this signal, then write(2) fails with the error EPIPE."
*/
if (dev->d_nreaders <= 0)
{
nxsem_post(&dev->d_bfsem);
return nwritten == 0 ? -EPIPE : nwritten;
}
/* Calculate the write index AFTER the next byte is written */
nxtwrndx = dev->d_wrndx + 1;
@ -595,7 +594,7 @@ ssize_t pipecommon_write(FAR struct file *filep, FAR const char *buffer,
* available.
*/
while (nxsem_get_value(&dev->d_rdsem, &sval) == 0 && sval < 0)
while (nxsem_get_value(&dev->d_rdsem, &sval) == 0 && sval <= 0)
{
nxsem_post(&dev->d_rdsem);
}
@ -624,7 +623,7 @@ ssize_t pipecommon_write(FAR struct file *filep, FAR const char *buffer,
* available.
*/
while (nxsem_get_value(&dev->d_rdsem, &sval) == 0 && sval < 0)
while (nxsem_get_value(&dev->d_rdsem, &sval) == 0 && sval <= 0)
{
nxsem_post(&dev->d_rdsem);
}
@ -651,16 +650,8 @@ ssize_t pipecommon_write(FAR struct file *filep, FAR const char *buffer,
* the pipe
*/
sched_lock();
nxsem_post(&dev->d_bfsem);
ret = nxsem_wait(&dev->d_wrsem);
sched_unlock();
if (dev->d_nreaders <= 0)
{
ret = -EPIPE;
}
if (ret < 0 || (ret = nxsem_wait(&dev->d_bfsem)) < 0)
{
/* Either call nxsem_wait may fail because a signal was