From: Oleg Nesterov Date: Wed, 29 Mar 2006 00:11:26 +0000 (-0800) Subject: [PATCH] make fork() atomic wrt pgrp/session signals X-Git-Tag: v2.6.17-rc1~173 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4a2c7a7837da1b91468e50426066d988050e4d56;p=pandora-kernel.git [PATCH] make fork() atomic wrt pgrp/session signals Eric W. Biederman wrote: > > Ok. SUSV3/Posix is clear, fork is atomic with respect > to signals. Either a signal comes before or after a > fork but not during. (See the rationale section). > http://www.opengroup.org/onlinepubs/000095399/functions/fork.html > > The tasklist_lock does not stop forks from adding to a process > group. The forks stall while the tasklist_lock is held, but a fork > that began before we grabbed the tasklist_lock simply completes > afterwards, and the child does not receive the signal. This also means that SIGSTOP or sig_kernel_coredump() signal can't be delivered to pgrp/session reliably. With this patch copy_process() returns -ERESTARTNOINTR when it detects a pending signal, fork() will be restarted transparently after handling the signals. This patch also deletes now unneeded "group_stop_count > 0" check, copy_process() can no longer succeed while group stop in progress. Signed-off-by: Oleg Nesterov Acked-By: Eric Biederman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed