Commit 2ef82d24 authored Jul 16, 2014 by Dexuan Cui Committed by Greg Kroah-Hartman Jul 17, 2014

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>

parent 1795cd9b

drivers/hv/hv_fcopy.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -246,8 +246,8 @@ void hv_fcopy_onchannelcallback(void *context)
	/*		/*
	* Send the information to the user-level daemon.		* Send the information to the user-level daemon.
	*/		*/
	fcopy_send_data();
	schedule_delayed_work(&fcopy_work, 5*HZ);		schedule_delayed_work(&fcopy_work, 5*HZ);
			fcopy_send_data();
	return;		return;
	}		}
	icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION \| ICMSGHDRFLAG_RESPONSE;		icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION \| ICMSGHDRFLAG_RESPONSE;

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