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afs: Wait for outstanding async calls before closing rxrpc socket

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The afs filesystem needs to wait for any outstanding asynchronous calls
(such as FS.GiveUpCallBacks cleaning up the callbacks lodged with a server)
to complete before closing the AF_RXRPC socket when unloading the module.

This may occur if the module is removed too quickly after unmounting all
filesystems.  This will produce an error report that looks like:

	AFS: Assertion failed
	1 == 0 is false
	0x1 == 0x0 is false
	------------[ cut here ]------------
	kernel BUG at ../fs/afs/rxrpc.c:135!
	...
	RIP: 0010:[<ffffffffa004111c>] afs_close_socket+0xec/0x107 [kafs]
	...
	Call Trace:
	 [<ffffffffa004a160>] afs_exit+0x1f/0x57 [kafs]
	 [<ffffffff810c30a0>] SyS_delete_module+0xec/0x17d
	 [<ffffffff81610417>] entry_SYSCALL_64_fastpath+0x12/0x6b

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David Howells 2016-04-07 17:23:03 +01:00 committed by David S. Miller
parent c64a73d584
commit 2f02f7aea7
1 changed files with 13 additions and 3 deletions
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16
fs/afs/rxrpc.c
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@ -65,6 +65,12 @@ static void afs_async_workfn(struct work_struct *work)
call->async_workfn(call); call->async_workfn(call);
} }
static int afs_wait_atomic_t(atomic_t *p)
{
schedule();
return 0;
}
/* /*
* open an RxRPC socket and bind it to be a server for callback notifications * open an RxRPC socket and bind it to be a server for callback notifications
* - the socket is left in blocking mode and non-blocking ops use MSG_DONTWAIT * - the socket is left in blocking mode and non-blocking ops use MSG_DONTWAIT
@ -126,13 +132,16 @@ void afs_close_socket(void)
{ {
_enter(""); _enter("");
wait_on_atomic_t(&afs_outstanding_calls, afs_wait_atomic_t,
TASK_UNINTERRUPTIBLE);
_debug("no outstanding calls");
sock_release(afs_socket); sock_release(afs_socket);
_debug("dework"); _debug("dework");
destroy_workqueue(afs_async_calls); destroy_workqueue(afs_async_calls);
ASSERTCMP(atomic_read(&afs_outstanding_skbs), ==, 0); ASSERTCMP(atomic_read(&afs_outstanding_skbs), ==, 0);
ASSERTCMP(atomic_read(&afs_outstanding_calls), ==, 0);
_leave(""); _leave("");
} }
@ -178,8 +187,6 @@ static void afs_free_call(struct afs_call *call)
{ {
_debug("DONE %p{%s} [%d]", _debug("DONE %p{%s} [%d]",
call, call->type->name, atomic_read(&afs_outstanding_calls)); call, call->type->name, atomic_read(&afs_outstanding_calls));
if (atomic_dec_return(&afs_outstanding_calls) == -1)
BUG();
ASSERTCMP(call->rxcall, ==, NULL); ASSERTCMP(call->rxcall, ==, NULL);
ASSERT(!work_pending(&call->async_work)); ASSERT(!work_pending(&call->async_work));
@ -188,6 +195,9 @@ static void afs_free_call(struct afs_call *call)
kfree(call->request); kfree(call->request);
kfree(call); kfree(call);
if (atomic_dec_and_test(&afs_outstanding_calls))
wake_up_atomic_t(&afs_outstanding_calls);
} }
/* /*