Drivers: hv: vmbus: avoid wait_for_completion() on crash

wait_for_completion() may sleep, it enables interrupts and this
is something we really want to avoid on crashes because interrupt
handlers can cause other crashes. Switch to the recently introduced
vmbus_wait_for_unload() doing busy wait instead.

Reported-by: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Radim Kr.má<rkrcmar@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index b40f429aaa136551142cc7be034be50c1d0caf42..f70e35278b94d5efc31c10681deb13a16173cc7d 100644 (file)
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -641,7 +641,7 @@ static void vmbus_unload_response(struct vmbus_channel_message_header *hdr)
        complete(&vmbus_connection.unload_event);
 }
 
-void vmbus_initiate_unload(void)
+void vmbus_initiate_unload(bool crash)
 {
        struct vmbus_channel_message_header hdr;
 
@@ -658,7 +658,7 @@ void vmbus_initiate_unload(void)
         * vmbus_initiate_unload() is also called on crash and the crash can be
         * happening in an interrupt context, where scheduling is impossible.
         */
-       if (!in_interrupt())
+       if (!crash)
                wait_for_completion(&vmbus_connection.unload_event);
        else
                vmbus_wait_for_unload();

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index fa86b2cb28b82721bd6a6ee492b3fd24db40d060..3b6dc001726989ebcf3ced6ec169cd8e726d9d74 100644 (file)
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -236,7 +236,7 @@ void vmbus_disconnect(void)
        /*
         * First send the unload request to the host.
         */
-       vmbus_initiate_unload();
+       vmbus_initiate_unload(false);
 
        if (vmbus_connection.work_queue) {
                drain_workqueue(vmbus_connection.work_queue);

diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index b9ea7f59036b7fe565e2b99d3243d7004b9df20a..b0299da9c2db5d486229f45dbf259ded1cfee243 100644 (file)
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -663,7 +663,7 @@ void hv_vss_onchannelcallback(void *);
 int hv_fcopy_init(struct hv_util_service *);
 void hv_fcopy_deinit(void);
 void hv_fcopy_onchannelcallback(void *);
-void vmbus_initiate_unload(void);
+void vmbus_initiate_unload(bool crash);
 
 static inline void hv_poll_channel(struct vmbus_channel *channel,
                                   void (*cb)(void *))

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 30ea8ad902e2e94d36dd01bc20a07b1558834a8a..c8f1671944d559621185c11ac6ed13beafcf14f8 100644 (file)
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1291,7 +1291,7 @@ static void hv_kexec_handler(void)
        int cpu;
 
        hv_synic_clockevents_cleanup();
-       vmbus_initiate_unload();
+       vmbus_initiate_unload(false);
        for_each_online_cpu(cpu)
                smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1);
        hv_cleanup();
@@ -1299,7 +1299,7 @@ static void hv_kexec_handler(void)
 
 static void hv_crash_handler(struct pt_regs *regs)
 {
-       vmbus_initiate_unload();
+       vmbus_initiate_unload(true);
        /*
         * In crash handler we can't schedule synic cleanup for all CPUs,
         * doing the cleanup for current CPU only. This should be sufficient