diff options
| author | Dexuan Cui <decui@microsoft.com> | 2015-12-14 16:01:47 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-09-15 08:27:40 +0200 |
| commit | ff83d7914b749f8c654c0e08d21667035901ab75 (patch) | |
| tree | 6a8bf43103f2fe841ba72e18d27b9debf6ca5c64 /drivers/hv | |
| parent | bf59c816fb104b2e92d29f8c13f1118f4c5333c4 (diff) | |
Drivers: hv: vmbus: serialize process_chn_event() and vmbus_close_internal()
[ Upstream commit 63d55b2aeb5e4faa170316fee73c3c47ea9268c7 ]
process_chn_event(), running in the tasklet, can race with
vmbus_close_internal() in the case of SMP guest, e.g., when the former is
accessing channel->inbound.ring_buffer, the latter could be freeing the
ring_buffer pages.
To resolve the race, we can serialize them by disabling the tasklet when
the latter is running here.
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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hv')
| -rw-r--r-- | drivers/hv/channel.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c index 9098f13f2f44..6a90c69bc71c 100644 --- a/drivers/hv/channel.c +++ b/drivers/hv/channel.c @@ -28,6 +28,7 @@ #include <linux/module.h> #include <linux/hyperv.h> #include <linux/uio.h> +#include <linux/interrupt.h> #include "hyperv_vmbus.h" @@ -496,8 +497,21 @@ static void reset_channel_cb(void *arg) static int vmbus_close_internal(struct vmbus_channel *channel) { struct vmbus_channel_close_channel *msg; + struct tasklet_struct *tasklet; int ret; + /* + * process_chn_event(), running in the tasklet, can race + * with vmbus_close_internal() in the case of SMP guest, e.g., when + * the former is accessing channel->inbound.ring_buffer, the latter + * could be freeing the ring_buffer pages. + * + * To resolve the race, we can serialize them by disabling the + * tasklet when the latter is running here. + */ + tasklet = hv_context.event_dpc[channel->target_cpu]; + tasklet_disable(tasklet); + channel->state = CHANNEL_OPEN_STATE; channel->sc_creation_callback = NULL; /* Stop callback and cancel the timer asap */ @@ -525,7 +539,7 @@ static int vmbus_close_internal(struct vmbus_channel *channel) * If we failed to post the close msg, * it is perhaps better to leak memory. */ - return ret; + goto out; } /* Tear down the gpadl for the channel's ring buffer */ @@ -538,7 +552,7 @@ static int vmbus_close_internal(struct vmbus_channel *channel) * If we failed to teardown gpadl, * it is perhaps better to leak memory. */ - return ret; + goto out; } } @@ -555,6 +569,9 @@ static int vmbus_close_internal(struct vmbus_channel *channel) if (channel->rescind) hv_process_channel_removal(channel, channel->offermsg.child_relid); +out: + tasklet_enable(tasklet); + return ret; } |