poweroff: change orderly_poweroff() to use schedule_work()
David said:
Commit 6c0c0d4d10
("poweroff: fix bug in orderly_poweroff()")
apparently fixes one bug in orderly_poweroff(), but introduces
another. The comments on orderly_poweroff() claim it can be called
from any context - and indeed we call it from interrupt context in
arch/powerpc/platforms/pseries/ras.c for example. But since that
commit this is no longer safe, since call_usermodehelper_fns() is not
safe in interrupt context without the UMH_NO_WAIT option.
orderly_poweroff() can be used from any context but UMH_WAIT_EXEC is
sleepable. Move the "force" logic into __orderly_poweroff() and change
orderly_poweroff() to use the global poweroff_work which simply calls
__orderly_poweroff().
While at it, remove the unneeded "int argc" and change argv_split() to
use GFP_KERNEL.
We use the global "bool poweroff_force" to pass the argument, this can
obviously affect the previous request if it is pending/running. So we
only allow the "false => true" transition assuming that the pending
"true" should succeed anyway. If schedule_work() fails after that we
know that work->func() was not called yet, it must see the new value.
This means that orderly_poweroff() becomes async even if we do not run
the command and always succeeds, schedule_work() can only fail if the
work is already pending. We can export __orderly_poweroff() and change
the non-atomic callers which want the old semantics.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reported-by: David Gibson <david@gibson.dropbear.id.au>
Cc: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Feng Hong <hongfeng@marvell.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
d00285884c
commit
2ca067efd8
55
kernel/sys.c
55
kernel/sys.c
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@ -2185,9 +2185,8 @@ SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep,
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char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
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static int __orderly_poweroff(void)
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static int __orderly_poweroff(bool force)
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{
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int argc;
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char **argv;
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static char *envp[] = {
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"HOME=/",
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@ -2196,35 +2195,19 @@ static int __orderly_poweroff(void)
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};
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int ret;
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argv = argv_split(GFP_ATOMIC, poweroff_cmd, &argc);
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if (argv == NULL) {
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argv = argv_split(GFP_KERNEL, poweroff_cmd, NULL);
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if (argv) {
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ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
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argv_free(argv);
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} else {
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printk(KERN_WARNING "%s failed to allocate memory for \"%s\"\n",
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__func__, poweroff_cmd);
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return -ENOMEM;
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ret = -ENOMEM;
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}
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ret = call_usermodehelper_fns(argv[0], argv, envp, UMH_WAIT_EXEC,
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NULL, NULL, NULL);
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argv_free(argv);
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return ret;
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}
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/**
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* orderly_poweroff - Trigger an orderly system poweroff
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* @force: force poweroff if command execution fails
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*
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* This may be called from any context to trigger a system shutdown.
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* If the orderly shutdown fails, it will force an immediate shutdown.
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*/
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int orderly_poweroff(bool force)
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{
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int ret = __orderly_poweroff();
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if (ret && force) {
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printk(KERN_WARNING "Failed to start orderly shutdown: "
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"forcing the issue\n");
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/*
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* I guess this should try to kick off some daemon to sync and
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* poweroff asap. Or not even bother syncing if we're doing an
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@ -2236,4 +2219,28 @@ int orderly_poweroff(bool force)
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return ret;
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}
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static bool poweroff_force;
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static void poweroff_work_func(struct work_struct *work)
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{
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__orderly_poweroff(poweroff_force);
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}
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static DECLARE_WORK(poweroff_work, poweroff_work_func);
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/**
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* orderly_poweroff - Trigger an orderly system poweroff
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* @force: force poweroff if command execution fails
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*
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* This may be called from any context to trigger a system shutdown.
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* If the orderly shutdown fails, it will force an immediate shutdown.
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*/
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int orderly_poweroff(bool force)
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{
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if (force) /* do not override the pending "true" */
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poweroff_force = true;
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schedule_work(&poweroff_work);
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return 0;
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}
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EXPORT_SYMBOL_GPL(orderly_poweroff);
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