https://github.com/torvalds/linux
Revision 86998aa6534e839ec003ed2ef7067d6fe8696ccc authored by Ingo Molnar on 19 September 2006, 09:14:34 UTC, committed by Linus Torvalds on 19 September 2006, 14:57:20 UTC
while porting the -rt tree to 2.6.18-rc7 i noticed the following screaming-IRQ scenario on an SMP system: 2274 0Dn.:1 0.001ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.010ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.020ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.029ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.039ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.048ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.058ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.068ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.077ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.087ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.097ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) as it turns out, the bug is caused by handle_level_irq(), which if it races with another CPU already handling this IRQ, it _unmasks_ the IRQ line on the way out. This is not how 2.6.17 works, and we introduced this bug in one of the early genirq cleanups right before it went into -mm. (the bug was not in the genirq patchset for a long time, and we didnt notice the bug due to the lack of -rt rebase to the new genirq code. -rt, and hardirq-preemption in particular opens up such races much wider than anything else.) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 parent 47a5c6f
Tip revision: 86998aa6534e839ec003ed2ef7067d6fe8696ccc authored by Ingo Molnar on 19 September 2006, 09:14:34 UTC
[PATCH] genirq core: fix handle_level_irq()
[PATCH] genirq core: fix handle_level_irq()
Tip revision: 86998aa
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arch | ||
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crypto | ||
drivers | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
scripts | ||
security | ||
sound | ||
usr | ||
.gitignore | -rw-r--r-- | 542 bytes |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 87.4 KB |
Kbuild | -rw-r--r-- | 1.2 KB |
MAINTAINERS | -rw-r--r-- | 71.2 KB |
Makefile | -rw-r--r-- | 46.5 KB |
README | -rw-r--r-- | 16.2 KB |
REPORTING-BUGS | -rw-r--r-- | 3.0 KB |
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