forked from Minki/linux
18374d89e5
John Blackwood reported: > on an older Dell PowerEdge 6650 system with 8 cpus (4 are hyper-threaded), > and 32 bit (x86) kernel, once you change the irq smp_affinity of an irq > to be less than all cpus in the system, you can never change really the > irq smp_affinity back to be all cpus in the system (0xff) again, > even though no error status is returned on the "/bin/echo ff > > /proc/irq/[n]/smp_affinity" operation. > > This is due to that fact that BAD_APICID has the same value as > all cpus (0xff) on 32bit kernels, and thus the value returned from > set_desc_affinity() via the cpu_mask_to_apicid_and() function is treated > as a failure in set_ioapic_affinity_irq_desc(), and no affinity changes > are made. set_desc_affinity() is already checking if the incoming cpu mask intersects with the cpu online mask or not. So there is no need for the apic op cpu_mask_to_apicid_and() to check again and return BAD_APICID. Remove the BAD_APICID return value from cpu_mask_to_apicid_and() and also fix set_desc_affinity() to return -1 instead of using BAD_APICID to represent error conditions (as cpu_mask_to_apicid_and() can return logical or physical apicid values and BAD_APICID is really to represent bad physical apic id). Reported-by: John Blackwood <john.blackwood@ccur.com> Root-caused-by: John Blackwood <john.blackwood@ccur.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <1261103386.2535.409.camel@sbs-t61> Signed-off-by: H. Peter Anvin <hpa@zytor.com> |
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