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Drivers: hv: hv_fcopy: fix a race condition for SMP guest

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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>
This commit is contained in:
Dexuan Cui 2014-07-16 00:00:45 -07:00 committed by Greg Kroah-Hartman
parent 1795cd9b3a
commit 2ef82d24f4
1 changed files with 1 additions and 1 deletions
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2
drivers/hv/hv_fcopy.c
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@ -246,8 +246,8 @@ void hv_fcopy_onchannelcallback(void *context)
/*
* 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;