From 416ad3c9c0066405b83ec875b75496523549be09 Mon Sep 17 00:00:00 2001 From: Colin Cross Date: Mon, 6 May 2013 23:50:06 +0000 Subject: 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 Acked-by: Pavel Machek Acked-by: Tejun Heo Signed-off-by: Rafael J. Wysocki --- net/sunrpc/sched.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/sunrpc/sched.c') diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index f8529fc8e54..8dcfadcef5d 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; } -- cgit v1.2.3-70-g09d2 From a76580fbf09e6e19c2040c08969af5137e064eda Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Mon, 20 May 2013 23:00:18 -0400 Subject: SUNRPC: Fix a potential race in rpc_execute If the rpc_task is asynchronous, it could theoretically finish executing on the workqueue it was assigned by rpc_make_runnable() before we get round to testing RPC_IS_ASYNC() in rpc_execute. In practice, however, all the existing callers hold a reference to the rpc_task, so this can't happen today... Signed-off-by: Trond Myklebust --- net/sunrpc/sched.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'net/sunrpc/sched.c') diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index 5356b120dbf..849ca413522 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -825,9 +825,11 @@ static void __rpc_execute(struct rpc_task *task) */ void rpc_execute(struct rpc_task *task) { + bool is_async = RPC_IS_ASYNC(task); + rpc_set_active(task); rpc_make_runnable(task); - if (!RPC_IS_ASYNC(task)) + if (!is_async) __rpc_execute(task); } -- cgit v1.2.3-70-g09d2 From 0053a8e65c0b949fd230488e5be871755f3f860f Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Tue, 21 May 2013 12:51:32 -0400 Subject: SUNRPC: Remove unused function rpc_queue_empty Signed-off-by: Trond Myklebust --- include/linux/sunrpc/sched.h | 1 - net/sunrpc/sched.c | 14 -------------- 2 files changed, 15 deletions(-) (limited to 'net/sunrpc/sched.c') diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h index 84ca436b76c..5e255ab893d 100644 --- a/include/linux/sunrpc/sched.h +++ b/include/linux/sunrpc/sched.h @@ -238,7 +238,6 @@ struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *, bool (*)(struct rpc_task *, void *), void *); void rpc_wake_up_status(struct rpc_wait_queue *, int); -int rpc_queue_empty(struct rpc_wait_queue *); void rpc_delay(struct rpc_task *, unsigned long); void * rpc_malloc(struct rpc_task *, size_t); void rpc_free(void *); diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index 849ca413522..dcbd69cb1cb 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -445,20 +445,6 @@ static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct r } } -/* - * Tests whether rpc queue is empty - */ -int rpc_queue_empty(struct rpc_wait_queue *queue) -{ - int res; - - spin_lock_bh(&queue->lock); - res = queue->qlen; - spin_unlock_bh(&queue->lock); - return res == 0; -} -EXPORT_SYMBOL_GPL(rpc_queue_empty); - /* * Wake up a task on a specific queue */ -- cgit v1.2.3-70-g09d2 From 9ec2ef53b92fdbb1b5f24af000fc2ba0b18221ea Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 22 May 2013 18:52:18 -0400 Subject: SUNRPC: Remove redundant call to rpc_set_running() in __rpc_execute() The RPC_TASK_RUNNING flag will always have been set in rpc_make_runnable() once we get past the test for out_of_line_wait_on_bit() returning ERESTARTSYS. Signed-off-by: Trond Myklebust --- net/sunrpc/sched.c | 1 - 1 file changed, 1 deletion(-) (limited to 'net/sunrpc/sched.c') diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index dcbd69cb1cb..b7b32c34c18 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -790,7 +790,6 @@ static void __rpc_execute(struct rpc_task *task) task->tk_flags |= RPC_TASK_KILLED; rpc_exit(task, -ERESTARTSYS); } - rpc_set_running(task); dprintk("RPC: %5u sync task resuming\n", task->tk_pid); } -- cgit v1.2.3-70-g09d2