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authorColin Cross <ccross@android.com>2013-05-06 23:50:06 +0000
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-05-12 14:16:21 +0200
commit416ad3c9c0066405b83ec875b75496523549be09 (patch)
tree393d8c261cf9b79c18197d3173e0b8aa8874ca35 /net/sunrpc
parentf722406faae2d073cc1d01063d1123c35425939e (diff)
freezer: add unsafe versions of freezable helpers for NFS
NFS calls the freezable helpers with locks held, which is unsafe and will cause lockdep warnings when 6aa9707 "lockdep: check that no locks held at freeze time" is reapplied (it was reverted in dbf520a). NFS shouldn't be doing this, but it has long-running syscalls that must hold a lock but also shouldn't block suspend. Until NFS freeze handling is rewritten to use a signal to exit out of the critical section, add new *_unsafe versions of the helpers that will not run the lockdep test when 6aa9707 is reapplied, and call them from NFS. In practice the likley result of holding the lock while freezing is that a second task blocked on the lock will never freeze, aborting suspend, but it is possible to manufacture a case using the cgroup freezer, the lock, and the suspend freezer to create a deadlock. Silencing the lockdep warning here will allow problems to be found in other drivers that may have a more serious deadlock risk, and prevent new problems from being added. Signed-off-by: Colin Cross <ccross@android.com> Acked-by: Pavel Machek <pavel@ucw.cz> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'net/sunrpc')
-rw-r--r--net/sunrpc/sched.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index f8529fc8e542..8dcfadcef5d3 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -254,7 +254,7 @@ static int rpc_wait_bit_killable(void *word)
{
if (fatal_signal_pending(current))
return -ERESTARTSYS;
- freezable_schedule();
+ freezable_schedule_unsafe();
return 0;
}