diff options
| -rw-r--r-- | drivers/hv/channel.c | 24 | ||||
| -rw-r--r-- | drivers/hv/channel_mgmt.c | 1 | ||||
| -rw-r--r-- | drivers/hv/vmbus_drv.c | 30 | ||||
| -rw-r--r-- | include/linux/hyperv.h | 6 |
4 files changed, 31 insertions, 30 deletions
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c index 256ee90c7446..132e476f87b2 100644 --- a/drivers/hv/channel.c +++ b/drivers/hv/channel.c @@ -594,15 +594,10 @@ post_msg_err: } EXPORT_SYMBOL_GPL(vmbus_teardown_gpadl); -static void reset_channel_cb(void *arg) -{ - struct vmbus_channel *channel = arg; - - channel->onchannel_callback = NULL; -} - void vmbus_reset_channel_cb(struct vmbus_channel *channel) { + unsigned long flags; + /* * vmbus_on_event(), running in the per-channel tasklet, can race * with vmbus_close_internal() in the case of SMP guest, e.g., when @@ -618,17 +613,12 @@ void vmbus_reset_channel_cb(struct vmbus_channel *channel) */ tasklet_disable(&channel->callback_event); - channel->sc_creation_callback = NULL; + /* See the inline comments in vmbus_chan_sched(). */ + spin_lock_irqsave(&channel->sched_lock, flags); + channel->onchannel_callback = NULL; + spin_unlock_irqrestore(&channel->sched_lock, flags); - /* 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(); - } + channel->sc_creation_callback = NULL; /* Re-enable tasklet for use on re-open */ tasklet_enable(&channel->callback_event); diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index bbd0eee4362f..2e730f84654b 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -315,6 +315,7 @@ static struct vmbus_channel *alloc_channel(void) if (!channel) return NULL; + spin_lock_init(&channel->sched_lock); spin_lock_init(&channel->lock); init_completion(&channel->rescind_event); diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index 21a01bca7fcd..0f7dfa507a40 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -1202,18 +1202,6 @@ static void vmbus_force_channel_rescinded(struct vmbus_channel *channel) #endif /* CONFIG_PM_SLEEP */ /* - * Direct callback for channels using other deferred processing - */ -static void vmbus_channel_isr(struct vmbus_channel *channel) -{ - void (*callback_fn)(void *); - - callback_fn = READ_ONCE(channel->onchannel_callback); - if (likely(callback_fn != NULL)) - (*callback_fn)(channel->channel_callback_context); -} - -/* * Schedule all channels with events pending */ static void vmbus_chan_sched(struct hv_per_cpu_context *hv_cpu) @@ -1243,6 +1231,7 @@ static void vmbus_chan_sched(struct hv_per_cpu_context *hv_cpu) return; for_each_set_bit(relid, recv_int_page, maxbits) { + void (*callback_fn)(void *context); struct vmbus_channel *channel; if (!sync_test_and_clear_bit(relid, recv_int_page)) @@ -1268,13 +1257,26 @@ static void vmbus_chan_sched(struct hv_per_cpu_context *hv_cpu) if (channel->rescind) goto sched_unlock_rcu; + /* + * Make sure that the ring buffer data structure doesn't get + * freed while we dereference the ring buffer pointer. Test + * for the channel's onchannel_callback being NULL within a + * sched_lock critical section. See also the inline comments + * in vmbus_reset_channel_cb(). + */ + spin_lock(&channel->sched_lock); + + callback_fn = channel->onchannel_callback; + if (unlikely(callback_fn == NULL)) + goto sched_unlock; + trace_vmbus_chan_sched(channel); ++channel->interrupts; switch (channel->callback_mode) { case HV_CALL_ISR: - vmbus_channel_isr(channel); + (*callback_fn)(channel->channel_callback_context); break; case HV_CALL_BATCHED: @@ -1284,6 +1286,8 @@ static void vmbus_chan_sched(struct hv_per_cpu_context *hv_cpu) tasklet_schedule(&channel->callback_event); } +sched_unlock: + spin_unlock(&channel->sched_lock); sched_unlock_rcu: rcu_read_unlock(); } diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index f5b3f008c55a..62b2c11d0875 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -772,6 +772,12 @@ struct vmbus_channel { void *channel_callback_context; /* + * Synchronize channel scheduling and channel removal; see the inline + * comments in vmbus_chan_sched() and vmbus_reset_channel_cb(). + */ + spinlock_t sched_lock; + + /* * A channel can be marked for one of three modes of reading: * BATCHED - callback called from taslket and should read * channel until empty. Interrupts from the host |