In preparation for removing printk's @logbuf_lock, dumpers that have assumed to be protected against parallel calls must provide their own synchronization. Add a locally static spinlock to synchronize the kmsg_dump call.
Signed-off-by: John Ogness <[email protected]> --- drivers/hv/vmbus_drv.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index fbeddef90941..08db95e1a139 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -1362,23 +1362,27 @@ static void hv_kmsg_dump(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason, struct kmsg_dumper_iter *iter) { + static DEFINE_SPINLOCK(lock); size_t bytes_written; phys_addr_t panic_pa; + unsigned long flags; /* We are only interested in panics. */ if ((reason != KMSG_DUMP_PANIC) || (!sysctl_record_panic_msg)) return; + if (!spin_trylock_irqsave(&lock, flags)) + return; + panic_pa = virt_to_phys(hv_panic_page); - /* - * Write dump contents to the page. No need to synchronize; panic should - * be single-threaded. - */ + /* Write dump contents to the page. */ kmsg_dump_get_buffer(iter, false, hv_panic_page, HV_HYP_PAGE_SIZE, &bytes_written); if (bytes_written) hyperv_report_panic_msg(panic_pa, bytes_written); + + spin_unlock_irqrestore(&lock, flags); } static struct kmsg_dumper hv_kmsg_dumper = { -- 2.20.1
