kern/94772: commit references a PR
dfilter service
dfilter at FreeBSD.ORG
Tue Jul 7 09:50:04 UTC 2009
The following reply was made to PR kern/94772; it has been noted by GNATS.
From: dfilter at FreeBSD.ORG (dfilter service)
To: bug-followup at FreeBSD.org
Cc:
Subject: Re: kern/94772: commit references a PR
Date: Tue, 7 Jul 2009 09:44:00 +0000 (UTC)
Author: kib
Date: Tue Jul 7 09:43:44 2009
New Revision: 195423
URL: http://svn.freebsd.org/changeset/base/195423
Log:
Fix poll(2) and select(2) for named pipes to return "ready for read"
when all writers, observed by reader, exited. Use writer generation
counter for fifo, and store the snapshot of the fifo generation in the
f_seqcount field of struct file, that is otherwise unused for fifos.
Set FreeBSD-undocumented POLLINIGNEOF flag only when file f_seqcount is
equal to fifo' fi_wgen, and revert r89376.
Fix POLLINIGNEOF for sockets and pipes, and return POLLHUP for them.
Note that the patch does not fix not returning POLLHUP for fifos.
PR: kern/94772
Submitted by: bde (original version)
Reviewed by: rwatson, jilles
Approved by: re (kensmith)
MFC after: 6 weeks (might be)
Modified:
head/sys/fs/fifofs/fifo_vnops.c
head/sys/kern/sys_pipe.c
head/sys/kern/uipc_socket.c
head/sys/sys/socketvar.h
Modified: head/sys/fs/fifofs/fifo_vnops.c
==============================================================================
--- head/sys/fs/fifofs/fifo_vnops.c Tue Jul 7 00:02:26 2009 (r195422)
+++ head/sys/fs/fifofs/fifo_vnops.c Tue Jul 7 09:43:44 2009 (r195423)
@@ -84,6 +84,7 @@ struct fifoinfo {
struct socket *fi_writesock;
long fi_readers;
long fi_writers;
+ int fi_wgen;
};
static vop_print_t fifo_print;
@@ -232,6 +233,7 @@ fail1:
sowwakeup(fip->fi_writesock);
}
}
+ fp->f_seqcount = fip->fi_wgen - fip->fi_writers;
}
if (ap->a_mode & FWRITE) {
if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
@@ -279,6 +281,9 @@ fail1:
fip->fi_writers--;
if (fip->fi_writers == 0) {
socantrcvmore(fip->fi_readsock);
+ mtx_lock(&fifo_mtx);
+ fip->fi_wgen++;
+ mtx_unlock(&fifo_mtx);
fifo_cleanup(vp);
}
return (error);
@@ -395,8 +400,12 @@ fifo_close(ap)
}
if (ap->a_fflag & FWRITE) {
fip->fi_writers--;
- if (fip->fi_writers == 0)
+ if (fip->fi_writers == 0) {
socantrcvmore(fip->fi_readsock);
+ mtx_lock(&fifo_mtx);
+ fip->fi_wgen++;
+ mtx_unlock(&fifo_mtx);
+ }
}
fifo_cleanup(vp);
return (0);
@@ -634,28 +643,13 @@ fifo_poll_f(struct file *fp, int events,
levents = events &
(POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
if ((fp->f_flag & FREAD) && levents) {
- /*
- * If POLLIN or POLLRDNORM is requested and POLLINIGNEOF is
- * not, then convert the first two to the last one. This
- * tells the socket poll function to ignore EOF so that we
- * block if there is no writer (and no data). Callers can
- * set POLLINIGNEOF to get non-blocking behavior.
- */
- if (levents & (POLLIN | POLLRDNORM) &&
- !(levents & POLLINIGNEOF)) {
- levents &= ~(POLLIN | POLLRDNORM);
- levents |= POLLINIGNEOF;
- }
-
filetmp.f_data = fip->fi_readsock;
filetmp.f_cred = cred;
+ mtx_lock(&fifo_mtx);
+ if (fp->f_seqcount == fip->fi_wgen)
+ levents |= POLLINIGNEOF;
+ mtx_unlock(&fifo_mtx);
revents |= soo_poll(&filetmp, levents, cred, td);
-
- /* Reverse the above conversion. */
- if ((revents & POLLINIGNEOF) && !(events & POLLINIGNEOF)) {
- revents |= (events & (POLLIN | POLLRDNORM));
- revents &= ~POLLINIGNEOF;
- }
}
levents = events & (POLLOUT | POLLWRNORM | POLLWRBAND);
if ((fp->f_flag & FWRITE) && levents) {
Modified: head/sys/kern/sys_pipe.c
==============================================================================
--- head/sys/kern/sys_pipe.c Tue Jul 7 00:02:26 2009 (r195422)
+++ head/sys/kern/sys_pipe.c Tue Jul 7 09:43:44 2009 (r195423)
@@ -1353,8 +1353,7 @@ pipe_poll(fp, events, active_cred, td)
#endif
if (events & (POLLIN | POLLRDNORM))
if ((rpipe->pipe_state & PIPE_DIRECTW) ||
- (rpipe->pipe_buffer.cnt > 0) ||
- (rpipe->pipe_state & PIPE_EOF))
+ (rpipe->pipe_buffer.cnt > 0))
revents |= events & (POLLIN | POLLRDNORM);
if (events & (POLLOUT | POLLWRNORM))
@@ -1364,10 +1363,14 @@ pipe_poll(fp, events, active_cred, td)
(wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
revents |= events & (POLLOUT | POLLWRNORM);
- if ((rpipe->pipe_state & PIPE_EOF) ||
- wpipe->pipe_present != PIPE_ACTIVE ||
- (wpipe->pipe_state & PIPE_EOF))
- revents |= POLLHUP;
+ if ((events & POLLINIGNEOF) == 0) {
+ if (rpipe->pipe_state & PIPE_EOF) {
+ revents |= (events & (POLLIN | POLLRDNORM));
+ if (wpipe->pipe_present != PIPE_ACTIVE ||
+ (wpipe->pipe_state & PIPE_EOF))
+ revents |= POLLHUP;
+ }
+ }
if (revents == 0) {
if (events & (POLLIN | POLLRDNORM)) {
Modified: head/sys/kern/uipc_socket.c
==============================================================================
--- head/sys/kern/uipc_socket.c Tue Jul 7 00:02:26 2009 (r195422)
+++ head/sys/kern/uipc_socket.c Tue Jul 7 09:43:44 2009 (r195423)
@@ -2885,14 +2885,9 @@ sopoll_generic(struct socket *so, int ev
SOCKBUF_LOCK(&so->so_snd);
SOCKBUF_LOCK(&so->so_rcv);
if (events & (POLLIN | POLLRDNORM))
- if (soreadable(so))
+ if (soreadabledata(so))
revents |= events & (POLLIN | POLLRDNORM);
- if (events & POLLINIGNEOF)
- if (so->so_rcv.sb_cc >= so->so_rcv.sb_lowat ||
- !TAILQ_EMPTY(&so->so_comp) || so->so_error)
- revents |= POLLINIGNEOF;
-
if (events & (POLLOUT | POLLWRNORM))
if (sowriteable(so))
revents |= events & (POLLOUT | POLLWRNORM);
@@ -2901,10 +2896,16 @@ sopoll_generic(struct socket *so, int ev
if (so->so_oobmark || (so->so_rcv.sb_state & SBS_RCVATMARK))
revents |= events & (POLLPRI | POLLRDBAND);
+ if ((events & POLLINIGNEOF) == 0) {
+ if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
+ revents |= events & (POLLIN | POLLRDNORM);
+ if (so->so_snd.sb_state & SBS_CANTSENDMORE)
+ revents |= POLLHUP;
+ }
+ }
+
if (revents == 0) {
- if (events &
- (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM |
- POLLRDBAND)) {
+ if (events & (POLLIN | POLLPRI | POLLRDNORM | POLLRDBAND)) {
selrecord(td, &so->so_rcv.sb_sel);
so->so_rcv.sb_flags |= SB_SEL;
}
Modified: head/sys/sys/socketvar.h
==============================================================================
--- head/sys/sys/socketvar.h Tue Jul 7 00:02:26 2009 (r195422)
+++ head/sys/sys/socketvar.h Tue Jul 7 09:43:44 2009 (r195423)
@@ -197,10 +197,11 @@ struct xsocket {
((so)->so_proto->pr_flags & PR_ATOMIC)
/* can we read something from so? */
-#define soreadable(so) \
+#define soreadabledata(so) \
((so)->so_rcv.sb_cc >= (so)->so_rcv.sb_lowat || \
- ((so)->so_rcv.sb_state & SBS_CANTRCVMORE) || \
!TAILQ_EMPTY(&(so)->so_comp) || (so)->so_error)
+#define soreadable(so) \
+ (soreadabledata(so) || ((so)->so_rcv.sb_state & SBS_CANTRCVMORE))
/* can we write something to so? */
#define sowriteable(so) \
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