Searched hist:"759 f4298" (Results 1 – 1 of 1) sorted by relevance
/openbmc/linux/net/9p/ |
H A D | trans_fd.c | 759f4298 Mon Sep 17 08:16:31 CDT 2012 Simon Derr <simon.derr@bull.net> 9P: Fix race between p9_write_work() and p9_fd_request()
Race scenario:
thread A thread B
p9_write_work() p9_fd_request()
if (list_empty (&m->unsent_req_list)) ...
spin_lock(&client->lock); req->status = REQ_STATUS_UNSENT; list_add_tail(..., &m->unsent_req_list); spin_unlock(&client->lock); .... if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched) schedule_work(&m->wq); --> not done because Wworksched is set
clear_bit(Wworksched, &m->wsched); return;
--> nobody will take care of sending the new request.
This is not very likely to happen though, because p9_write_work() being called with an empty unsent_req_list is not frequent. But this also means that taking the lock earlier will not be costly.
Signed-off-by: Simon Derr <simon.derr@bull.net> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com> 759f4298 Mon Sep 17 08:16:31 CDT 2012 Simon Derr <simon.derr@bull.net> 9P: Fix race between p9_write_work() and p9_fd_request() Race scenario: thread A thread B p9_write_work() p9_fd_request() if (list_empty (&m->unsent_req_list)) ... spin_lock(&client->lock); req->status = REQ_STATUS_UNSENT; list_add_tail(..., &m->unsent_req_list); spin_unlock(&client->lock); .... if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched) schedule_work(&m->wq); --> not done because Wworksched is set clear_bit(Wworksched, &m->wsched); return; --> nobody will take care of sending the new request. This is not very likely to happen though, because p9_write_work() being called with an empty unsent_req_list is not frequent. But this also means that taking the lock earlier will not be costly. Signed-off-by: Simon Derr <simon.derr@bull.net> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
|