Messages in this thread | | | Date | Wed, 2 May 2007 03:48:22 +0400 | From | Oleg Nesterov <> | Subject | Re: libata-core.c: unsafe cancel_delayed_work() usage? |
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On 05/01, Jeff Garzik wrote: > > Oleg Nesterov wrote: > > > >Alan, the usage of cancel_delayed_work() in drivers/ata/libata-core.c looks > >suspicious to me, both ->hotplug_task and ->port_task can re-arm > >themselves, > >so cancel_delayed_work + flush_workqueue (or cancel_work_sync) is not > >enough. > > > >Could you confirm/nack my understanding? > > For all rearming workqueues, one must use cancel-rearming-blahblah.
Well, yes and no. cancel_rearming_delayed_work() requires that dwork re-arms itself unconditionally, otherwise it just hangs (actually, the patch to fix this shortcoming is ready). However, ata_pio_task() for example, re-arms only when ATA_BUSY.
So it is very possible that the code is correct, if the caller of ata_port_flush_task() ensures that ATA_BUSY is not possible. Otherwise we should change cancel_rearming_delayed_work() and use it.
Oleg.
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