Messages in this thread | | | Subject | Re: Potential race condition in drivers/ata/sata_mv.ko | From | Pavel Andrianov <> | Date | Thu, 11 Aug 2016 17:18:31 +0300 |
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Hi!
I have found such example:
... ->
ata_exec_internal_sg ->
ata_qc_issue ->
mv_qc_issue ->
mv_clear_and_enable_port_irqs ->
mv_enable_port_irqs ->
mv_set_main_irq_mask
ata_exec_internal_sg acquires spin_lock(ap->lock) and call of the last function mv_set_main_irq_mask is with this lock. mv_interrupt acquires spin_lock(host->lock) before call of the same function. I am not sure is it correct to add one more spin_lock or move a call of request_irq in ata_host_activate, thus I can not easily fix the issue.
One more question is related to ata_exec_internal_sg. In comments there is an information the function is called without locking. However, ata_exec_internal_sg calls ata_eh_release before ata_eh_acquire (lines 1650, 1655).There is a block of code under spinlock and eh context can not be acquired there. The comment may be wrong and eh_context is acquired somewhere before, but I also can not find it. Do you know where is the initial acquire of eh_context in this case?
10.08.2016 06:51, Tejun Heo пишет: > Hello, > > On Fri, Aug 05, 2016 at 03:43:30PM +0300, Pavel Andrianov wrote: >> In drivers/ata/sata_mv.ko function mv_set_main_irq_mask is called several >> times. Twice with a spinlock, twice from init function and once without any >> protection. The call without protection rises to several handlers from >> ata_port_operations. The structure with the ata_port_operations is included >> into a structure 'host' in mv_platform_probe and in mv_pci_init_one. At the >> end of these functions ata_host operations are activated together with >> interrupt handler. The conclusion is: interrupt handler may be executed in >> parallel with handlers from ata_port_operations, or, more formally, it may >> interrupt its execution. >> >> In mv_set_main_irq_mask and in interrupt handler mv_interrupt the interrupt >> mask is modified, but, as I said, handlers from ata_port_operations do not >> acquire any lock. Thus, the interrupt mask may be set incorrectly if the are >> two conflicting modifications. > It depends on which operations. Most are only called from EH context > and racing there isn't likely to cause any actual issues. Care to > submit a patch to fix the issue? > > Thanks. >
-- Pavel Andrianov Linux Verification Center, ISPRAS web: http://linuxtesting.org e-mail: andrianov@ispras.ru
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