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authorGuilherme G. Piccoli <gpiccoli@igalia.com>2022-03-15 17:35:35 -0300
committerWei Liu <wei.liu@kernel.org>2022-03-29 12:05:12 +0000
commit792f232d57ff28bbd5f9c4abe0466b23d5879dc8 (patch)
tree8659d9f6788996a802b01f3be16a7ad71c0c8eaf /drivers/hv
parent3a5469582c241abca22500f36a9cb8e9331969cf (diff)
downloadlinux-792f232d57ff28bbd5f9c4abe0466b23d5879dc8.tar.bz2
Drivers: hv: vmbus: Fix potential crash on module unload
The vmbus driver relies on the panic notifier infrastructure to perform some operations when a panic event is detected. Since vmbus can be built as module, it is required that the driver handles both registering and unregistering such panic notifier callback. After commit 74347a99e73a ("x86/Hyper-V: Unload vmbus channel in hv panic callback") though, the panic notifier registration is done unconditionally in the module initialization routine whereas the unregistering procedure is conditionally guarded and executes only if HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE capability is set. This patch fixes that by unconditionally unregistering the panic notifier in the module's exit routine as well. Fixes: 74347a99e73a ("x86/Hyper-V: Unload vmbus channel in hv panic callback") Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/20220315203535.682306-1-gpiccoli@igalia.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
Diffstat (limited to 'drivers/hv')
-rw-r--r--drivers/hv/vmbus_drv.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index df22fbdc2ae2..6c057c76c2ca 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -2787,10 +2787,15 @@ static void __exit vmbus_exit(void)
if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
kmsg_dump_unregister(&hv_kmsg_dumper);
unregister_die_notifier(&hyperv_die_block);
- atomic_notifier_chain_unregister(&panic_notifier_list,
- &hyperv_panic_block);
}
+ /*
+ * The panic notifier is always registered, hence we should
+ * also unconditionally unregister it here as well.
+ */
+ atomic_notifier_chain_unregister(&panic_notifier_list,
+ &hyperv_panic_block);
+
free_page((unsigned long)hv_panic_page);
unregister_sysctl_table(hv_ctl_table_hdr);
hv_ctl_table_hdr = NULL;