Messages in this thread | | | Date | Wed, 6 Nov 2013 17:56:46 -0800 | From | Greg KH <> | Subject | Re: [PATCH] devres: Freeing the drs after all release() are called |
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On Thu, Nov 07, 2013 at 01:18:54AM +0000, Liu, Chuansheng wrote: > Hello, > > > -----Original Message----- > > From: Tejun Heo [mailto:htejun@gmail.com] On Behalf Of tj@kernel.org > > Sent: Thursday, November 07, 2013 8:52 AM > > To: Liu, Chuansheng > > Cc: Greg KH; dmitry.torokhov@gmail.com; linux-kernel@vger.kernel.org > > Subject: Re: [PATCH] devres: Freeing the drs after all release() are called > > > > Hello, > > > > On Thu, Nov 07, 2013 at 12:36:56AM +0000, Liu, Chuansheng wrote: > > > Yes, I knew I can put the code always like below: > > > A = devm_kzalloc(); > > > C = devm_kzalloc(); > > > ... > > > B= devm_request_threaded_irq(isr_handler); > > > > > > But, the above is just one simple coding prototype, if there are many calling: > > > E -- > F -- > D -- >... then to devm_kzalloc(). > > > > > > To be honest, it will make code too hard to always adapt the rule? > > > And I trying to find out every potential devm_kzalloc() before irq requesting. > > > > It isn't a good idea to paper over existing bugs from upper layer. > > You realize that the above code sequence is already buggy during init > > unless there's something explicitly blocking generation of irqs until > > init is complete, right? The right thing to do would be either > > reordering the operations or wrapping the operation which unblocks irq > > at the end of init with devres so that irq gets blocked before the > > rest of release proceeds. > > > > What we must *NOT* do is working around existing bugs in a half-assed > > way from midlayer. > > Yes, doing the right order initialization is always right thing. > But normally when we hit the panic during shutdown/reboot like below: > PAGE FAULT XXX 0x12345678 > > It is really difficult to debug. > So at least, could we have method to expose these hidden issues?
Have you enabled timer debugging? I think there's an irq debugging option as well.
We aren't going to paper over driver bugs by changing the kernel core, sorry. Consider this patch dropped.
greg k-h
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