Date: Wed, 14 Dec 2011 22:30:11 GMT From: dfilter@FreeBSD.ORG (dfilter service) To: freebsd-bugs@FreeBSD.org Subject: Re: kern/93685: commit references a PR Message-ID: <201112142230.pBEMUBRi005258@freefall.freebsd.org>
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The following reply was made to PR kern/93685; it has been noted by GNATS. From: dfilter@FreeBSD.ORG (dfilter service) To: bug-followup@FreeBSD.org Cc: Subject: Re: kern/93685: commit references a PR Date: Wed, 14 Dec 2011 22:26:53 +0000 (UTC) Author: jilles Date: Wed Dec 14 22:26:39 2011 New Revision: 228510 URL: http://svn.freebsd.org/changeset/base/228510 Log: Fix select/poll/kqueue for write on reverse direction before first write. The reverse direction of a pipe is lazily allocated on the first write in that direction (because pipes are usually used in one direction only). A special case is needed to ensure the pipe appears writable before the first write because there are 0 bytes of pending data in 0 bytes of buffer space at that point, leaving 0 bytes of data that can be written with the normal code. Note that the first write returns [ENOMEM] if kern.ipc.maxpipekva is exceeded and does not block or return [EAGAIN], so selecting true for write is correct even in that case. PR: kern/93685 Submitted by: gianni MFC after: 2 weeks Modified: head/sys/kern/sys_pipe.c Modified: head/sys/kern/sys_pipe.c ============================================================================== --- head/sys/kern/sys_pipe.c Wed Dec 14 22:22:19 2011 (r228509) +++ head/sys/kern/sys_pipe.c Wed Dec 14 22:26:39 2011 (r228510) @@ -1349,7 +1349,8 @@ pipe_poll(fp, events, active_cred, td) if (wpipe->pipe_present != PIPE_ACTIVE || (wpipe->pipe_state & PIPE_EOF) || (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && - (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF)) + ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || + wpipe->pipe_buffer.size == 0))) revents |= events & (POLLOUT | POLLWRNORM); if ((events & POLLINIGNEOF) == 0) { @@ -1660,7 +1661,8 @@ filt_pipewrite(struct knote *kn, long hi PIPE_UNLOCK(rpipe); return (1); } - kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; + kn->kn_data = (wpipe->pipe_buffer.size > 0) ? + (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF; if (wpipe->pipe_state & PIPE_DIRECTW) kn->kn_data = 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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