diff options
| author | Liu Ping Fan <kernelfans@gmail.com> | 2013-08-23 16:58:47 +0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-08-26 12:58:00 +0200 |
| commit | 25aa2957973d361081ac6c8b6e5a0d9d7a83fef6 (patch) | |
| tree | ad77338c9f70a2dd2f4c731e71e1a4cd12c29fee /arch/x86/kernel/apic | |
| parent | 17405453f4ad0220721a29978692081be6392b8f (diff) | |
| download | linux-25aa2957973d361081ac6c8b6e5a0d9d7a83fef6.tar.bz2 | |
x86/ioapic: Check attr against the previous setting when programmed more than once
When programming ioapic pinX more than once, current code
does not check whether the later attr (trigger & polarity) is the
same as the former or not.
This causes broken semantics which can be observed in a qemu q35
machine, where ioapic's ioredtbl[x] can never be set as low-active,
even if the hpet driver registered it.
And hpet driver may share a high-level active IRQ line with other
devices. So in qemu, when hpet-dev asserts low-level as kernel
expects, the kernel has no response.
With this patch, we can observe an ioredtbl[x] set as low-active
for hpet.
Fix it by reporting -EBUSY to the caller, when attr is different.
Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
Cc: Kevin Hao <haokexin@gmail.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1377248327-19633-1-git-send-email-pingfank@linux.vnet.ibm.com
[ Made small readability edits to both the changelog and the code. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/apic')
| -rw-r--r-- | arch/x86/kernel/apic/io_apic.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 260abc2f9eeb..e63a5bd2a78f 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -3380,12 +3380,15 @@ int io_apic_setup_irq_pin_once(unsigned int irq, int node, { unsigned int ioapic_idx = attr->ioapic, pin = attr->ioapic_pin; int ret; + struct IO_APIC_route_entry orig_entry; /* Avoid redundant programming */ if (test_bit(pin, ioapics[ioapic_idx].pin_programmed)) { - pr_debug("Pin %d-%d already programmed\n", - mpc_ioapic_id(ioapic_idx), pin); - return 0; + pr_debug("Pin %d-%d already programmed\n", mpc_ioapic_id(ioapic_idx), pin); + orig_entry = ioapic_read_entry(attr->ioapic, pin); + if (attr->trigger == orig_entry.trigger && attr->polarity == orig_entry.polarity) + return 0; + return -EBUSY; } ret = io_apic_setup_irq_pin(irq, node, attr); if (!ret) |