Author: kib
Date: Wed Mar 7 07:31:50 2012
New Revision: 232641
URL: http://svn.freebsd.org/changeset/base/232641
Log:
The pipe_poll() performs lockless access to the vnode to test
fifo_iseof() condition, allowing the v_fifoinfo to be reset and freed
by fifo_cleanup().
Precalculate EOF at the places were fo_wgen is changed, and cache the
state in a new pipe state flag PIPE_SAMEWGEN.
Reported and tested by: bf
Submitted by: gianni
MFC after: 1 week (a backport)
Modified:
head/sys/fs/fifofs/fifo.h
head/sys/fs/fifofs/fifo_vnops.c
head/sys/kern/sys_pipe.c
head/sys/sys/pipe.h
Modified: head/sys/fs/fifofs/fifo.h
==============================================================================
--- head/sys/fs/fifofs/fifo.h Wed Mar 7 07:22:53 2012 (r232640)
+++ head/sys/fs/fifofs/fifo.h Wed Mar 7 07:31:50 2012 (r232641)
@@ -33,7 +33,6 @@
/*
* Prototypes for fifo operations on vnodes.
*/
-int fifo_iseof(struct file *);
int fifo_vnoperate(struct vop_generic_args *);
int fifo_printinfo(struct vnode *);
Modified: head/sys/fs/fifofs/fifo_vnops.c
==============================================================================
--- head/sys/fs/fifofs/fifo_vnops.c Wed Mar 7 07:22:53 2012
(r232640)
+++ head/sys/fs/fifofs/fifo_vnops.c Wed Mar 7 07:31:50 2012
(r232641)
@@ -67,8 +67,16 @@ struct fifoinfo {
long fi_readers;
long fi_writers;
int fi_wgen;
+ int fi_seqcount;
};
+#define FIFO_UPDWGEN(fip, pip) do { \
+ if ((fip)->fi_wgen == (fip)->fi_seqcount) \
+ (pip)->pipe_state |= PIPE_SAMEWGEN; \
+ else \
+ (pip)->pipe_state &= ~PIPE_SAMEWGEN; \
+} while (0)
+
static vop_print_t fifo_print;
static vop_open_t fifo_open;
static vop_close_t fifo_close;
@@ -174,7 +182,8 @@ fifo_open(ap)
if (fip->fi_writers > 0)
wakeup(&fip->fi_writers);
}
- fp->f_seqcount = fip->fi_wgen - fip->fi_writers;
+ fip->fi_seqcount = fip->fi_wgen - fip->fi_writers;
+ FIFO_UPDWGEN(fip, fpipe);
}
if (ap->a_mode & FWRITE) {
if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
@@ -228,6 +237,7 @@ fifo_open(ap)
if (fpipe->pipe_state & PIPE_WANTR)
wakeup(fpipe);
fip->fi_wgen++;
+ FIFO_UPDWGEN(fip, fpipe);
PIPE_UNLOCK(fpipe);
fifo_cleanup(vp);
}
@@ -287,6 +297,7 @@ fifo_close(ap)
if (cpipe->pipe_state & PIPE_WANTR)
wakeup(cpipe);
fip->fi_wgen++;
+ FIFO_UPDWGEN(fip, cpipe);
PIPE_UNLOCK(cpipe);
}
}
@@ -373,15 +384,3 @@ fifo_advlock(ap)
return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL);
}
-int
-fifo_iseof(struct file *fp)
-{
- struct fifoinfo *fip;
-
- KASSERT(fp->f_vnode != NULL, ("fifo_iseof: no vnode info"));
- KASSERT(fp->f_vnode->v_fifoinfo != NULL, ("fifo_iseof: no fifoinfo"));
- fip = fp->f_vnode->v_fifoinfo;
- PIPE_LOCK_ASSERT(fip->fi_pipe, MA_OWNED);
- return (fp->f_seqcount == fip->fi_wgen);
-}
-
Modified: head/sys/kern/sys_pipe.c
==============================================================================
--- head/sys/kern/sys_pipe.c Wed Mar 7 07:22:53 2012 (r232640)
+++ head/sys/kern/sys_pipe.c Wed Mar 7 07:31:50 2012 (r232641)
@@ -1430,7 +1430,7 @@ pipe_poll(fp, events, active_cred, td)
levents = events &
(POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents &&
- fifo_iseof(fp))
+ rpipe->pipe_state & PIPE_SAMEWGEN)
events |= POLLINIGNEOF;
if ((events & POLLINIGNEOF) == 0) {
Modified: head/sys/sys/pipe.h
==============================================================================
--- head/sys/sys/pipe.h Wed Mar 7 07:22:53 2012 (r232640)
+++ head/sys/sys/pipe.h Wed Mar 7 07:31:50 2012 (r232641)
@@ -96,6 +96,7 @@ struct pipemapping {
#define PIPE_DIRECTW 0x400 /* Pipe direct write active. */
#define PIPE_DIRECTOK 0x800 /* Direct mode ok. */
#define PIPE_NAMED 0x1000 /* Is a named pipe. */
+#define PIPE_SAMEWGEN 0x2000 /* same write generation for named pipes. */
/*
* Per-pipe data structure.
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