[PATCH 2/2] Drivers: hv: vmbus: Properly protect calls to smp_processor_id()

From: K. Y. Srinivasan
Date: Thu Aug 28 2014 - 20:26:38 EST


Disable preemption when sampling current processor ID when preemption
is otherwise possible.

Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
---
drivers/hv/channel.c | 7 +++++--
drivers/hv/channel_mgmt.c | 21 +++++++++++++++------
2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 19bad59..433f72a 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -486,11 +486,14 @@ 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 != smp_processor_id())
+ if (channel->target_cpu != get_cpu()) {
+ put_cpu();
smp_call_function_single(channel->target_cpu, reset_channel_cb,
channel, true);
- else
+ } else {
reset_channel_cb(channel);
+ put_cpu();
+ }

/* Send a closing message */

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index ed9350d..a2d1a96 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -224,11 +224,14 @@ static void vmbus_process_rescind_offer(struct work_struct *work)
msg.header.msgtype = CHANNELMSG_RELID_RELEASED;
vmbus_post_msg(&msg, sizeof(struct vmbus_channel_relid_released));

- if (channel->target_cpu != smp_processor_id())
+ if (channel->target_cpu != get_cpu()) {
+ put_cpu();
smp_call_function_single(channel->target_cpu,
percpu_channel_deq, channel, true);
- else
+ } else {
percpu_channel_deq(channel);
+ put_cpu();
+ }

if (channel->primary_channel == NULL) {
spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
@@ -294,12 +297,15 @@ static void vmbus_process_offer(struct work_struct *work)
spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);

if (enq) {
- if (newchannel->target_cpu != smp_processor_id())
+ if (newchannel->target_cpu != get_cpu()) {
+ put_cpu();
smp_call_function_single(newchannel->target_cpu,
percpu_channel_enq,
newchannel, true);
- else
+ } else {
percpu_channel_enq(newchannel);
+ put_cpu();
+ }
}
if (!fnew) {
/*
@@ -314,12 +320,15 @@ static void vmbus_process_offer(struct work_struct *work)
list_add_tail(&newchannel->sc_list, &channel->sc_list);
spin_unlock_irqrestore(&channel->sc_lock, flags);

- if (newchannel->target_cpu != smp_processor_id())
+ if (newchannel->target_cpu != get_cpu()) {
+ put_cpu();
smp_call_function_single(newchannel->target_cpu,
percpu_channel_enq,
newchannel, true);
- else
+ } else {
percpu_channel_enq(newchannel);
+ put_cpu();
+ }

newchannel->state = CHANNEL_OPEN_STATE;
if (channel->sc_creation_callback != NULL)
--
1.7.4.1

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