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author | Brandon Philips <bphilips@suse.de> | 2010-02-07 13:02:50 -0800 |
---|---|---|
committer | H. Peter Anvin <hpa@zytor.com> | 2010-02-18 21:53:15 -0800 |
commit | eb5b3794062824ba12d883901eea49ea89d0a678 (patch) | |
tree | a0a53204d7efa00d11ded6bcc166c36dbdd087d6 /arch | |
parent | 0a832320f1bae6a4169bf683e201378f2437cfc1 (diff) | |
download | linux-stable-eb5b3794062824ba12d883901eea49ea89d0a678.tar.gz linux-stable-eb5b3794062824ba12d883901eea49ea89d0a678.tar.bz2 linux-stable-eb5b3794062824ba12d883901eea49ea89d0a678.zip |
x86, irq: Keep chip_data in create_irq_nr and destroy_irq
Version 4: use get_irq_chip_data() in destroy_irq() to get rid of some
local vars.
When two drivers are setting up MSI-X at the same time via
pci_enable_msix() there is a race. See this dmesg excerpt:
[ 85.170610] ixgbe 0000:02:00.1: irq 97 for MSI/MSI-X
[ 85.170611] alloc irq_desc for 99 on node -1
[ 85.170613] igb 0000:08:00.1: irq 98 for MSI/MSI-X
[ 85.170614] alloc kstat_irqs on node -1
[ 85.170616] alloc irq_2_iommu on node -1
[ 85.170617] alloc irq_desc for 100 on node -1
[ 85.170619] alloc kstat_irqs on node -1
[ 85.170621] alloc irq_2_iommu on node -1
[ 85.170625] ixgbe 0000:02:00.1: irq 99 for MSI/MSI-X
[ 85.170626] alloc irq_desc for 101 on node -1
[ 85.170628] igb 0000:08:00.1: irq 100 for MSI/MSI-X
[ 85.170630] alloc kstat_irqs on node -1
[ 85.170631] alloc irq_2_iommu on node -1
[ 85.170635] alloc irq_desc for 102 on node -1
[ 85.170636] alloc kstat_irqs on node -1
[ 85.170639] alloc irq_2_iommu on node -1
[ 85.170646] BUG: unable to handle kernel NULL pointer dereference
at 0000000000000088
As you can see igb and ixgbe are both alternating on create_irq_nr()
via pci_enable_msix() in their probe function.
ixgbe: While looping through irq_desc_ptrs[] via create_irq_nr() ixgbe
choses irq_desc_ptrs[102] and exits the loop, drops vector_lock and
calls dynamic_irq_init. Then it sets irq_desc_ptrs[102]->chip_data =
NULL via dynamic_irq_init().
igb: Grabs the vector_lock now and starts looping over irq_desc_ptrs[]
via create_irq_nr(). It gets to irq_desc_ptrs[102] and does this:
cfg_new = irq_desc_ptrs[102]->chip_data;
if (cfg_new->vector != 0)
continue;
This hits the NULL deref.
Another possible race exists via pci_disable_msix() in a driver or in
the number of error paths that call free_msi_irqs():
destroy_irq()
dynamic_irq_cleanup() which sets desc->chip_data = NULL
...race window...
desc->chip_data = cfg;
Remove the save and restore code for cfg in create_irq_nr() and
destroy_irq() and take the desc->lock when checking the irq_cfg.
Reported-and-analyzed-by: Brandon Philips <bphilips@suse.de>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20100207210250.GB8256@jenkins.home.ifup.org>
Signed-off-by: Brandon Phiilps <bphilips@suse.de>
Cc: stable@kernel.org
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/kernel/apic/io_apic.c | 20 |
1 files changed, 5 insertions, 15 deletions
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 5e4cce254e43..e93a76bc8670 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -3278,12 +3278,9 @@ unsigned int create_irq_nr(unsigned int irq_want, int node) } spin_unlock_irqrestore(&vector_lock, flags); - if (irq > 0) { - dynamic_irq_init(irq); - /* restore it, in case dynamic_irq_init clear it */ - if (desc_new) - desc_new->chip_data = cfg_new; - } + if (irq > 0) + dynamic_irq_init_keep_chip_data(irq); + return irq; } @@ -3305,19 +3302,12 @@ int create_irq(void) void destroy_irq(unsigned int irq) { unsigned long flags; - struct irq_cfg *cfg; - struct irq_desc *desc; - /* store it, in case dynamic_irq_cleanup clear it */ - desc = irq_to_desc(irq); - cfg = desc->chip_data; - dynamic_irq_cleanup(irq); - /* connect back irq_cfg */ - desc->chip_data = cfg; + dynamic_irq_cleanup_keep_chip_data(irq); free_irte(irq); spin_lock_irqsave(&vector_lock, flags); - __clear_irq_vector(irq, cfg); + __clear_irq_vector(irq, get_irq_chip_data(irq)); spin_unlock_irqrestore(&vector_lock, flags); } |