Messages in this thread | | | Subject | RE: [PATCH] ARCH: Fix 32-bit x86 MSI-X allocation leakage | Date | Mon, 28 Apr 2008 13:42:40 -0700 | From | "Waskiewicz Jr, Peter P" <> |
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> On Fri, 25 Apr 2008, PJ Waskiewicz wrote: > > This bug was introduced in the 2.6.24 i386/x86_64 tree merge, where > > Can you please explain what exactly caused the bug. > Definitely not the move from arch/i386 to arch/x86 as the > code there was not changed at all and has not be changed since then. > > CC'ed Eric as well.
Eric replied with the actual commit during the 2.6.24 merge window that introduced this bug. The io_apic.c code from the i386 tree did not stay completely static when it was merged into the x86 io_apic_32.c code. Here is the commit that Eric identified that introduced the defect:
In particular commit dbeb2be21d678c49a8d8bbf774903df15dd55474 Author: Rusty Russell <rusty@rustcorp.com.au> Date: Fri Oct 19 20:35:03 2007 +0200
i386: introduce "used_vectors" bitmap which can be used to reserve vectors.
This simplifies the io_apic.c __assign_irq_vector() logic and removes the explicit SYSCALL_VECTOR check, and also allows for vectors to be reserved by other mechanisms (ie. lguest).
[ tglx: arch/x86 adaptation ]
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Basically the code introduced the test_and_set_bit() on the used_vectors bitmap, but it didn't have a corresponding clear_bit() on IRQ destruction.
Cheers, -PJ Waskiewicz
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