From 14a73f54798f39854e521fb596da7d50b7566bbd Mon Sep 17 00:00:00 2001 From: Carl Henrik Lunde Date: Thu, 12 Jun 2008 20:13:58 +0200 Subject: [PATCH] block: disable IRQs until data is written to relay channel As we may run relay_reserve from interrupt context we must always disable IRQs. This is because a call to relay_reserve may expose previously written data to use space. Updated new message code and an old but related comment. Signed-off-by: Carl Henrik Lunde Signed-off-by: Jens Axboe Signed-off-by: Linus Torvalds --- block/blktrace.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/block/blktrace.c b/block/blktrace.c index 7ae87cc..8d3a277 100644 --- a/block/blktrace.c +++ b/block/blktrace.c @@ -79,16 +79,17 @@ void __trace_note_message(struct blk_trace *bt, const char *fmt, ...) { int n; va_list args; + unsigned long flags; char *buf; - preempt_disable(); + local_irq_save(flags); buf = per_cpu_ptr(bt->msg_data, smp_processor_id()); va_start(args, fmt); n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args); va_end(args); trace_note(bt, 0, BLK_TN_MESSAGE, buf, n); - preempt_enable(); + local_irq_restore(flags); } EXPORT_SYMBOL_GPL(__trace_note_message); @@ -158,10 +159,7 @@ void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, /* * A word about the locking here - we disable interrupts to reserve * some space in the relay per-cpu buffer, to prevent an irq - * from coming in and stepping on our toes. Once reserved, it's - * enough to get preemption disabled to prevent read of this data - * before we are through filling it. get_cpu()/put_cpu() does this - * for us + * from coming in and stepping on our toes. */ local_irq_save(flags); -- 2.7.4