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author | Oleg Nesterov <oleg@redhat.com> | 2013-03-22 23:04:41 +0100 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-03-23 00:41:20 +0100 |
commit | 2ca067efd82939dfd87827d29d36a265823a4c2f (patch) | |
tree | a6291128f65ef015ab36460a5e5f39a5bc25c4a1 /kernel/sys.c | |
parent | mm/hugetlb: fix total hugetlbfs pages count when using memory overcommit acco... (diff) | |
download | linux-2ca067efd82939dfd87827d29d36a265823a4c2f.tar.xz linux-2ca067efd82939dfd87827d29d36a265823a4c2f.zip |
poweroff: change orderly_poweroff() to use schedule_work()
David said:
Commit 6c0c0d4d1080 ("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>
Diffstat (limited to 'kernel/sys.c')
-rw-r--r-- | kernel/sys.c | 57 |
1 files changed, 32 insertions, 25 deletions
diff --git a/kernel/sys.c b/kernel/sys.c index 81f56445fba9..39c9c4a2949f 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2185,9 +2185,8 @@ SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep, char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff"; -static int __orderly_poweroff(void) +static int __orderly_poweroff(bool force) { - int argc; char **argv; static char *envp[] = { "HOME=/", @@ -2196,20 +2195,40 @@ static int __orderly_poweroff(void) }; int ret; - argv = argv_split(GFP_ATOMIC, poweroff_cmd, &argc); - if (argv == NULL) { + argv = argv_split(GFP_KERNEL, poweroff_cmd, NULL); + if (argv) { + ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); + argv_free(argv); + } else { printk(KERN_WARNING "%s failed to allocate memory for \"%s\"\n", - __func__, poweroff_cmd); - return -ENOMEM; + __func__, poweroff_cmd); + ret = -ENOMEM; } - ret = call_usermodehelper_fns(argv[0], argv, envp, UMH_WAIT_EXEC, - NULL, NULL, NULL); - argv_free(argv); + if (ret && force) { + printk(KERN_WARNING "Failed to start orderly shutdown: " + "forcing the issue\n"); + /* + * I guess this should try to kick off some daemon to sync and + * poweroff asap. Or not even bother syncing if we're doing an + * emergency shutdown? + */ + emergency_sync(); + kernel_power_off(); + } return ret; } +static bool poweroff_force; + +static void poweroff_work_func(struct work_struct *work) +{ + __orderly_poweroff(poweroff_force); +} + +static DECLARE_WORK(poweroff_work, poweroff_work_func); + /** * orderly_poweroff - Trigger an orderly system poweroff * @force: force poweroff if command execution fails @@ -2219,21 +2238,9 @@ static int __orderly_poweroff(void) */ int orderly_poweroff(bool force) { - int ret = __orderly_poweroff(); - - if (ret && force) { - printk(KERN_WARNING "Failed to start orderly shutdown: " - "forcing the issue\n"); - - /* - * I guess this should try to kick off some daemon to sync and - * poweroff asap. Or not even bother syncing if we're doing an - * emergency shutdown? - */ - emergency_sync(); - kernel_power_off(); - } - - return ret; + if (force) /* do not override the pending "true" */ + poweroff_force = true; + schedule_work(&poweroff_work); + return 0; } EXPORT_SYMBOL_GPL(orderly_poweroff); |