Module Name: src Committed By: hannken Date: Sat Oct 2 07:35:41 UTC 2021
Modified Files: src/sys/kern: sys_pipe.c Log Message: Fix a deadlock where one thread writes to a pipe, has more data and no space in the pipe and waits on "pipe_wcv" while the reader is closing the pipe and waits on "pipe_draincv". Swap the test for "PIPE_EOF" and the "cv_wait_sig()" in "pipe_write()". PR bin/56422 "zgrep -l sometimes hangs" To generate a diff of this commit: cvs rdiff -u -r1.156 -r1.157 src/sys/kern/sys_pipe.c Please note that diffs are not public domain; they are subject to the copyright notices on the relevant files.
Modified files: Index: src/sys/kern/sys_pipe.c diff -u src/sys/kern/sys_pipe.c:1.156 src/sys/kern/sys_pipe.c:1.157 --- src/sys/kern/sys_pipe.c:1.156 Mon Sep 27 00:51:10 2021 +++ src/sys/kern/sys_pipe.c Sat Oct 2 07:35:40 2021 @@ -1,4 +1,4 @@ -/* $NetBSD: sys_pipe.c,v 1.156 2021/09/27 00:51:10 thorpej Exp $ */ +/* $NetBSD: sys_pipe.c,v 1.157 2021/10/02 07:35:40 hannken Exp $ */ /*- * Copyright (c) 2003, 2007, 2008, 2009 The NetBSD Foundation, Inc. @@ -68,7 +68,7 @@ */ #include <sys/cdefs.h> -__KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.156 2021/09/27 00:51:10 thorpej Exp $"); +__KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.157 2021/10/02 07:35:40 hannken Exp $"); #include <sys/param.h> #include <sys/systm.h> @@ -694,11 +694,6 @@ pipe_write(file_t *fp, off_t *offset, st break; } - pipeunlock(wpipe); - error = cv_wait_sig(&wpipe->pipe_wcv, lock); - (void)pipelock(wpipe, false); - if (error != 0) - break; /* * If read side wants to go away, we just issue a signal * to ourselves. @@ -707,6 +702,12 @@ pipe_write(file_t *fp, off_t *offset, st error = EPIPE; break; } + + pipeunlock(wpipe); + error = cv_wait_sig(&wpipe->pipe_wcv, lock); + (void)pipelock(wpipe, false); + if (error != 0) + break; wakeup_state = wpipe->pipe_state; } }