Author: markj
Date: Sat Jul 6 00:59:11 2019
New Revision: 349773
URL: https://svnweb.freebsd.org/changeset/base/349773
Log:
MFC r349546:
Fix mutual exclusion in pipe_direct_write().
Modified:
stable/12/sys/kern/sys_pipe.c
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/sys/kern/sys_pipe.c
==============================================================================
--- stable/12/sys/kern/sys_pipe.c Fri Jul 5 22:48:31 2019
(r349772)
+++ stable/12/sys/kern/sys_pipe.c Sat Jul 6 00:59:11 2019
(r349773)
@@ -726,7 +726,7 @@ pipe_read(struct file *fp, struct uio *uio, struct ucr
rpipe->pipe_map.pos += size;
rpipe->pipe_map.cnt -= size;
if (rpipe->pipe_map.cnt == 0) {
- rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW);
+ rpipe->pipe_state &= ~PIPE_WANTW;
wakeup(rpipe);
}
#endif
@@ -857,13 +857,17 @@ pipe_build_write_buffer(struct pipe *wpipe, struct uio
}
/*
- * unmap and unwire the process buffer
+ * Unwire the process buffer.
*/
static void
pipe_destroy_write_buffer(struct pipe *wpipe)
{
PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
+ KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
+ ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
+
+ wpipe->pipe_state &= ~PIPE_DIRECTW;
vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages);
wpipe->pipe_map.npages = 0;
}
@@ -882,13 +886,15 @@ pipe_clone_write_buffer(struct pipe *wpipe)
int pos;
PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
+ KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
+ ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
+
size = wpipe->pipe_map.cnt;
pos = wpipe->pipe_map.pos;
wpipe->pipe_buffer.in = size;
wpipe->pipe_buffer.out = 0;
wpipe->pipe_buffer.cnt = size;
- wpipe->pipe_state &= ~PIPE_DIRECTW;
PIPE_UNLOCK(wpipe);
iov.iov_base = wpipe->pipe_buffer.buffer;
@@ -927,7 +933,7 @@ retry:
pipeunlock(wpipe);
goto error1;
}
- while (wpipe->pipe_state & PIPE_DIRECTW) {
+ if (wpipe->pipe_state & PIPE_DIRECTW) {
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
@@ -970,8 +976,7 @@ retry:
goto error1;
}
- error = 0;
- while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
+ while (wpipe->pipe_map.cnt != 0) {
if (wpipe->pipe_state & PIPE_EOF) {
pipe_destroy_write_buffer(wpipe);
pipeselwakeup(wpipe);
@@ -989,20 +994,19 @@ retry:
error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
"pipdwt", 0);
pipelock(wpipe, 0);
+ if (error != 0)
+ break;
}
if (wpipe->pipe_state & PIPE_EOF)
error = EPIPE;
- if (wpipe->pipe_state & PIPE_DIRECTW) {
- /*
- * this bit of trickery substitutes a kernel buffer for
- * the process that might be going away.
- */
+ if (error == EINTR || error == ERESTART)
pipe_clone_write_buffer(wpipe);
- } else {
+ else
pipe_destroy_write_buffer(wpipe);
- }
pipeunlock(wpipe);
+ KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0,
+ ("pipe %p leaked PIPE_DIRECTW", wpipe));
return (error);
error1:
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