Date: Sat, 28 Aug 2010 17:50:10 GMT From: dfilter@FreeBSD.ORG (dfilter service) To: freebsd-bugs@FreeBSD.org Subject: Re: kern/143029: commit references a PR Message-ID: <201008281750.o7SHoAsK015475@freefall.freebsd.org>
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The following reply was made to PR kern/143029; it has been noted by GNATS. From: dfilter@FreeBSD.ORG (dfilter service) To: bug-followup@FreeBSD.org Cc: Subject: Re: kern/143029: commit references a PR Date: Sat, 28 Aug 2010 17:42:22 +0000 (UTC) Author: kib Date: Sat Aug 28 17:42:08 2010 New Revision: 211941 URL: http://svn.freebsd.org/changeset/base/211941 Log: For some file types, select code registers two selfd structures. E.g., for socket, when specified POLLIN|POLLOUT in events, you would have one selfd registered for receiving socket buffer, and one for sending. Now, if both events are not ready to fire at the time of the initial scan, but are simultaneously ready after the sleep, pollrescan() would iterate over the pollfd struct twice. Since both times revents is not zero, returned value would be off by one. Fix this by recalculating the return value in pollout(). PR: kern/143029 MFC after: 2 weeks Modified: head/sys/kern/sys_generic.c Modified: head/sys/kern/sys_generic.c ============================================================================== --- head/sys/kern/sys_generic.c Sat Aug 28 17:38:40 2010 (r211940) +++ head/sys/kern/sys_generic.c Sat Aug 28 17:42:08 2010 (r211941) @@ -76,7 +76,8 @@ static MALLOC_DEFINE(M_IOCTLOPS, "ioctlo static MALLOC_DEFINE(M_SELECT, "select", "select() buffer"); MALLOC_DEFINE(M_IOV, "iov", "large iov's"); -static int pollout(struct pollfd *, struct pollfd *, u_int); +static int pollout(struct thread *, struct pollfd *, struct pollfd *, + u_int); static int pollscan(struct thread *, struct pollfd *, u_int); static int pollrescan(struct thread *); static int selscan(struct thread *, fd_mask **, fd_mask **, int); @@ -1207,7 +1208,7 @@ done: if (error == EWOULDBLOCK) error = 0; if (error == 0) { - error = pollout(bits, uap->fds, nfds); + error = pollout(td, bits, uap->fds, nfds); if (error) goto out; } @@ -1262,22 +1263,27 @@ pollrescan(struct thread *td) static int -pollout(fds, ufds, nfd) +pollout(td, fds, ufds, nfd) + struct thread *td; struct pollfd *fds; struct pollfd *ufds; u_int nfd; { int error = 0; u_int i = 0; + u_int n = 0; for (i = 0; i < nfd; i++) { error = copyout(&fds->revents, &ufds->revents, sizeof(ufds->revents)); if (error) return (error); + if (fds->revents != 0) + n++; fds++; ufds++; } + td->td_retval[0] = n; return (0); } _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscribe@freebsd.org"
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