The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From dde9f095583b3f375ba23979045ee10dfcebec2f Mon Sep 17 00:00:00 2001

From: David Howells dhowells@redhat.com Date: Fri, 13 Mar 2020 13:46:08 +0000 Subject: [PATCH] afs: Fix handling of an abort from a service handler

When an AFS service handler function aborts a call, AF_RXRPC marks the call as complete - which means that it's not going to get any more packets from the receiver. This is a problem because reception of the final ACK is what triggers afs_deliver_to_call() to drop the final ref on the afs_call object.

Instead, aborted AFS service calls may then just sit around waiting for ever or until they're displaced by a new call on the same connection channel or a connection-level abort.

Fix this by calling afs_set_call_complete() to finalise the afs_call struct representing the call.

However, we then need to drop the ref that stops the call from being deallocated. We can do this in afs_set_call_complete(), as the work queue is holding a separate ref of its own, but then we shouldn't do it in afs_process_async_call() and afs_delete_async_call().

call->drop_ref is set to indicate that a ref needs dropping for a call and this is dealt with when we transition a call to AFS_CALL_COMPLETE.

But then we also need to get rid of the ref that pins an asynchronous client call. We can do this by the same mechanism, setting call->drop_ref for an async client call too.

We can also get rid of call->incoming since nothing ever sets it and only one thing ever checks it (futilely).

A trace of the rxrpc_call and afs_call struct ref counting looks like:

<idle>-0 [001] ..s5 164.764892: rxrpc_call: c=00000002 SEE u=3 sp=rxrpc_new_incoming_call+0x473/0xb34 a=00000000442095b5 <idle>-0 [001] .Ns5 164.766001: rxrpc_call: c=00000002 QUE u=4 sp=rxrpc_propose_ACK+0xbe/0x551 a=00000000442095b5 <idle>-0 [001] .Ns4 164.766005: rxrpc_call: c=00000002 PUT u=3 sp=rxrpc_new_incoming_call+0xa3f/0xb34 a=00000000442095b5 <idle>-0 [001] .Ns7 164.766433: afs_call: c=00000002 WAKE u=2 o=11 sp=rxrpc_notify_socket+0x196/0x33c kworker/1:2-1810 [001] ...1 164.768409: rxrpc_call: c=00000002 SEE u=3 sp=rxrpc_process_call+0x25/0x7ae a=00000000442095b5 kworker/1:2-1810 [001] ...1 164.769439: rxrpc_tx_packet: c=00000002 e9f1a7a8:95786a88:00000008:09c5 00000001 00000000 02 22 ACK CallAck kworker/1:2-1810 [001] ...1 164.769459: rxrpc_call: c=00000002 PUT u=2 sp=rxrpc_process_call+0x74f/0x7ae a=00000000442095b5 kworker/1:2-1810 [001] ...1 164.770794: afs_call: c=00000002 QUEUE u=3 o=12 sp=afs_deliver_to_call+0x449/0x72c kworker/1:2-1810 [001] ...1 164.770829: afs_call: c=00000002 PUT u=2 o=12 sp=afs_process_async_call+0xdb/0x11e kworker/1:2-1810 [001] ...2 164.771084: rxrpc_abort: c=00000002 95786a88:00000008 s=0 a=1 e=1 K-1 kworker/1:2-1810 [001] ...1 164.771461: rxrpc_tx_packet: c=00000002 e9f1a7a8:95786a88:00000008:09c5 00000002 00000000 04 00 ABORT CallAbort kworker/1:2-1810 [001] ...1 164.771466: afs_call: c=00000002 PUT u=1 o=12 sp=SRXAFSCB_ProbeUuid+0xc1/0x106

The abort generated in SRXAFSCB_ProbeUuid(), labelled "K-1", indicates that the local filesystem/cache manager didn't recognise the UUID as its own.

Fixes: 2067b2b3f484 ("afs: Fix the CB.ProbeUuid service handler to reply correctly") Signed-off-by: David Howells dhowells@redhat.com

diff --git a/fs/afs/cmservice.c b/fs/afs/cmservice.c index ff3994a6be23..6765949b3aab 100644 --- a/fs/afs/cmservice.c +++ b/fs/afs/cmservice.c @@ -243,6 +243,17 @@ static void afs_cm_destructor(struct afs_call *call) call->buffer = NULL; }

+/* + * Abort a service call from within an action function. + */ +static void afs_abort_service_call(struct afs_call *call, u32 abort_code, int error, + const char *why) +{ + rxrpc_kernel_abort_call(call->net->socket, call->rxcall, + abort_code, error, why); + afs_set_call_complete(call, error, 0); +} + /* * The server supplied a list of callbacks that it wanted to break. */ @@ -510,8 +521,7 @@ static void SRXAFSCB_ProbeUuid(struct work_struct *work) if (memcmp(r, &call->net->uuid, sizeof(call->net->uuid)) == 0) afs_send_empty_reply(call); else - rxrpc_kernel_abort_call(call->net->socket, call->rxcall, - 1, 1, "K-1"); + afs_abort_service_call(call, 1, 1, "K-1");

afs_put_call(call); _leave(""); diff --git a/fs/afs/internal.h b/fs/afs/internal.h index 1d81fc4c3058..52de2112e1b1 100644 --- a/fs/afs/internal.h +++ b/fs/afs/internal.h @@ -154,7 +154,7 @@ struct afs_call { }; unsigned char unmarshall; /* unmarshalling phase */ unsigned char addr_ix; /* Address in ->alist */ - bool incoming; /* T if incoming call */ + bool drop_ref; /* T if need to drop ref for incoming call */ bool send_pages; /* T if data from mapping should be sent */ bool need_attention; /* T if RxRPC poked us */ bool async; /* T if asynchronous */ @@ -1209,8 +1209,16 @@ static inline void afs_set_call_complete(struct afs_call *call, ok = true; } spin_unlock_bh(&call->state_lock); - if (ok) + if (ok) { trace_afs_call_done(call); + + /* Asynchronous calls have two refs to release - one from the alloc and + * one queued with the work item - and we can't just deallocate the + * call because the work item may be queued again. + */ + if (call->drop_ref) + afs_put_call(call); + } }

/* diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c index 907d5948564a..972e3aafa361 100644 --- a/fs/afs/rxrpc.c +++ b/fs/afs/rxrpc.c @@ -18,7 +18,6 @@ struct workqueue_struct *afs_async_calls;

static void afs_wake_up_call_waiter(struct sock *, struct rxrpc_call *, unsigned long); static void afs_wake_up_async_call(struct sock *, struct rxrpc_call *, unsigned long); -static void afs_delete_async_call(struct work_struct *); static void afs_process_async_call(struct work_struct *); static void afs_rx_new_call(struct sock *, struct rxrpc_call *, unsigned long); static void afs_rx_discard_new_call(struct rxrpc_call *, unsigned long); @@ -402,8 +401,10 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp) /* If the call is going to be asynchronous, we need an extra ref for * the call to hold itself so the caller need not hang on to its ref. */ - if (call->async) + if (call->async) { afs_get_call(call, afs_call_trace_get); + call->drop_ref = true; + }

/* create a call */ rxcall = rxrpc_kernel_begin_call(call->net->socket, srx, call->key, @@ -585,8 +586,6 @@ static void afs_deliver_to_call(struct afs_call *call) done: if (call->type->done) call->type->done(call); - if (state == AFS_CALL_COMPLETE && call->incoming) - afs_put_call(call); out: _leave(""); return; @@ -745,21 +744,6 @@ static void afs_wake_up_async_call(struct sock *sk, struct rxrpc_call *rxcall, } }

-/* - * Delete an asynchronous call. The work item carries a ref to the call struct - * that we need to release. - */ -static void afs_delete_async_call(struct work_struct *work) -{ - struct afs_call *call = container_of(work, struct afs_call, async_work); - - _enter(""); - - afs_put_call(call); - - _leave(""); -} - /* * Perform I/O processing on an asynchronous call. The work item carries a ref * to the call struct that we either need to release or to pass on. @@ -775,16 +759,6 @@ static void afs_process_async_call(struct work_struct *work) afs_deliver_to_call(call); }

- if (call->state == AFS_CALL_COMPLETE) { - /* We have two refs to release - one from the alloc and one - * queued with the work item - and we can't just deallocate the - * call because the work item may be queued again. - */ - call->async_work.func = afs_delete_async_call; - if (!queue_work(afs_async_calls, &call->async_work)) - afs_put_call(call); - } - afs_put_call(call); _leave(""); } @@ -811,6 +785,7 @@ void afs_charge_preallocation(struct work_struct *work) if (!call) break;

+ call->drop_ref = true; call->async = true; call->state = AFS_CALL_SV_AWAIT_OP_ID; init_waitqueue_head(&call->waitq);