[BKL] add 'might_sleep()' to the outermost lock taker
As shown by the previous patch (6698e3472: "tty: Fix BKL taken under a spinlock bug introduced in the BKL split") the BKL removal is prone to some subtle issues, where removing the BKL in one place may in fact make a previously nested BKL call the new outer call, and then prone to nasty deadlocks with other spinlocks. In general, we should never take the BKL while we're holding a spinlock, so let's just add a "might_sleep()" to it (even though the BKL doesn't technically sleep - at least not yet), and we'll get nice warnings the next time this kind of problem happens during BKL removal. Acked-and-Tested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -122,8 +122,10 @@ void __lockfunc _lock_kernel(const char *func, const char *file, int line)
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trace_lock_kernel(func, file, line);
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if (likely(!depth))
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if (likely(!depth)) {
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might_sleep();
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__lock_kernel();
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}
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current->lock_depth = depth;
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}
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