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Fix poll(2) and select(2) for named pipes to return "ready for read"

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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)
This commit is contained in:
Konstantin Belousov 2009-07-07 09:43:44 +00:00
parent 55b57bd274
commit 7f5dff5064
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=195423
4 changed files with 36 additions and 37 deletions
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34
sys/fs/fifofs/fifo_vnops.c
View File

@ -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 @@ fifo_open(ap)
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 @@ fifo_open(ap)
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, struct ucred *cred, struct thread *td)
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) {

15
sys/kern/sys_pipe.c
View File

@ -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)) {

19
sys/kern/uipc_socket.c
View File

@ -2885,14 +2885,9 @@ sopoll_generic(struct socket *so, int events, struct ucred *active_cred,
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 events, struct ucred *active_cred,
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;
}

5
sys/sys/socketvar.h
View File

@ -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) \