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Drivers: hv: vmbus: Reset the channel callback in vmbus_onoffer_rescind()

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Before setting channel->rescind in vmbus_rescind_cleanup(), we should make
sure the channel callback won't run any more, otherwise a high-level
driver like pci_hyperv, which may be infinitely waiting for the host VSP's
response and notices the channel has been rescinded, can't safely give
up: e.g., in hv_pci_protocol_negotiation() -> wait_for_response(), it's
unsafe to exit from wait_for_response() and proceed with the on-stack
variable "comp_pkt" popped. The issue was originally spotted by
Michael Kelley <mikelley@microsoft.com>.

In vmbus_close_internal(), the patch also minimizes the range protected by
disabling/enabling channel->callback_event: we don't really need that for
the whole function.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Cc: stable@vger.kernel.org
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Michael Kelley <mikelley@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 2018-08-02 03:08:23 +00:00 committed by Greg Kroah-Hartman
parent 7026a5fd7f
commit d3b26dd7cb
3 changed files with 32 additions and 16 deletions
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40
drivers/hv/channel.c
View File

@ -558,11 +558,8 @@ static void reset_channel_cb(void *arg)
channel->onchannel_callback = NULL;
}
static int vmbus_close_internal(struct vmbus_channel *channel)
void vmbus_reset_channel_cb(struct vmbus_channel *channel)
{
struct vmbus_channel_close_channel *msg;
int ret;
/*
* vmbus_on_event(), running in the per-channel tasklet, can race
* with vmbus_close_internal() in the case of SMP guest, e.g., when
@ -572,6 +569,29 @@ static int vmbus_close_internal(struct vmbus_channel *channel)
*/
tasklet_disable(&channel->callback_event);
channel->sc_creation_callback = NULL;
/* Stop the callback asap */
if (channel->target_cpu != get_cpu()) {
put_cpu();
smp_call_function_single(channel->target_cpu, reset_channel_cb,
channel, true);
} else {
reset_channel_cb(channel);
put_cpu();
}
/* Re-enable tasklet for use on re-open */
tasklet_enable(&channel->callback_event);
}
static int vmbus_close_internal(struct vmbus_channel *channel)
{
struct vmbus_channel_close_channel *msg;
int ret;
vmbus_reset_channel_cb(channel);
/*
* In case a device driver's probe() fails (e.g.,
* util_probe() -> vmbus_open() returns -ENOMEM) and the device is
@ -585,16 +605,6 @@ static int vmbus_close_internal(struct vmbus_channel *channel)
}
channel->state = CHANNEL_OPEN_STATE;
channel->sc_creation_callback = NULL;
/* Stop callback and cancel the timer asap */
if (channel->target_cpu != get_cpu()) {
put_cpu();
smp_call_function_single(channel->target_cpu, reset_channel_cb,
channel, true);
} else {
reset_channel_cb(channel);
put_cpu();
}
/* Send a closing message */
@ -639,8 +649,6 @@ static int vmbus_close_internal(struct vmbus_channel *channel)
get_order(channel->ringbuffer_pagecount * PAGE_SIZE));
out:
/* re-enable tasklet for use on re-open */
tasklet_enable(&channel->callback_event);
return ret;
}

6
drivers/hv/channel_mgmt.c
View File

@ -892,6 +892,12 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
return;
}
/*
* Before setting channel->rescind in vmbus_rescind_cleanup(), we
* should make sure the channel callback is not running any more.
*/
vmbus_reset_channel_cb(channel);
/*
* Now wait for offer handling to complete.
*/

2
include/linux/hyperv.h
View File

@ -1061,6 +1061,8 @@ extern int vmbus_establish_gpadl(struct vmbus_channel *channel,
extern int vmbus_teardown_gpadl(struct vmbus_channel *channel,
u32 gpadl_handle);
void vmbus_reset_channel_cb(struct vmbus_channel *channel);
extern int vmbus_recvpacket(struct vmbus_channel *channel,
void *buffer,
u32 bufferlen,