Drivers: hv: hv_fcopy: fix a race condition for SMP guest
We should schedule the 5s "timer work" before starting the data transfer,
otherwise, the data transfer code may finish so fast on another
virtual cpu that when the code(fcopy_write()) trying to cancel the 5s
"timer work" can occasionally fail because the "timer work" may haven't
been scheduled yet and as a result the fcopy process will be aborted
wrongly by fcopy_work_func() in 5s.
Thank Liz Zhang <lizzha@microsoft.com> for the initial investigation
on the bug.
This addresses https://bugzilla.redhat.com/show_bug.cgi?id=1118123
Tested-by: Liz Zhang <lizzha@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hv/hv_fcopy.c b/drivers/hv/hv_fcopy.c
index eaaa3d8..23b2ce2 100644
--- a/drivers/hv/hv_fcopy.c
+++ b/drivers/hv/hv_fcopy.c
@@ -246,8 +246,8 @@
/*
* Send the information to the user-level daemon.
*/
- fcopy_send_data();
schedule_delayed_work(&fcopy_work, 5*HZ);
+ fcopy_send_data();
return;
}
icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
