From: Oleg Nesterov Date: Tue, 30 Apr 2013 22:28:15 +0000 (-0700) Subject: coredump: introduce dump_interrupted() X-Git-Tag: omap-for-v3.10/dt-fixes-for-merge-window~88^2~40 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=528f827ee0bb508af5c9466562f474675540473e;p=pandora-kernel.git coredump: introduce dump_interrupted() By discussion with Mandeep. Change dump_write(), dump_seek() and do_coredump() to check signal_pending() and abort if it is true. dump_seek() does this only before f_op->llseek(), otherwise it relies on dump_write(). We need this change to ensure that the coredump won't delay suspend, and to ensure it reacts to SIGKILL "quickly enough", a core dump can take a lot of time. In particular this can help oom-killer. We add the new trivial helper, dump_interrupted() to add the comments and to simplify the potential freezer changes. Perhaps it will have more callers. Ideally it should do try_to_freeze() but then we need the unpleasant changes in dump_write() and wait_for_dump_helpers(). It is not trivial to change dump_write() to restart if f_op->write() fails because of freezing(). We need to handle the short writes, we need to clear TIF_SIGPENDING (and we can't rely on recalc_sigpending() unless we change it to check PF_DUMPCORE). And if the buggy f_op->write() sets TIF_SIGPENDING we can not distinguish this case from the race with freeze_task() + __thaw_task(). So we simply accept the fact that the freezer can truncate a core-dump but at least you can reliably suspend. Hopefully we can tolerate this unlikely case and the necessary complications doesn't worth a trouble. But if we decide to make the coredumping freezable later we can do this on top of this change. Signed-off-by: Oleg Nesterov Acked-by: Mandeep Singh Baines Cc: Neil Horman Cc: "Rafael J. Wysocki" Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed