Messages in this thread | | | Date | Thu, 15 Mar 2012 07:10:36 +0100 (CET) | From | Julia Lawall <> | Subject | Re: [PATCH 7/7] arch/unicore32/kernel/dma.c: ensure arguments to request_irq and free_irq are compatible |
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On Thu, 15 Mar 2012, Guan Xuetao wrote:
> On Wed, 2012-03-14 at 10:23 +0100, Julia Lawall wrote: >> >> On Wed, 14 Mar 2012, Guan Xuetao wrote: >> >>> On Wed, 2012-03-14 at 11:19 +0300, Dan Carpenter wrote: >>>> On Wed, Mar 14, 2012 at 04:07:24PM +0800, Guan Xuetao wrote: >>>>> puv3_init_dma() is called ONCE when initializing. >>>>> In logical, if request_irq(IRQ_DMAERR, *) failed, free_irq(IRQ_DMA, *) >>>>> is unnecessary, and dma device/driver can keep on working. >>>>> The patch could be: >>>>> ret = request_irq(IRQ_DMAERR, dma_err_handler, 0, "DMAERR", NULL); >>>>> if (ret) { >>>>> printk(KERN_CRIT "Can't register IRQ for DMAERR\n"); >>>>> - free_irq(IRQ_DMA, "DMA"); >>>>> return ret; >>>>> } >>>> >>>> It seems like you should remove the error return as well? >>>> >>>> regards, >>>> dan carpenter >>>> >>> The error return value will only generate an extra warning message, and >>> have no side-effect. >> >> The whole thing seems a little strange. I guess your point is that the >> call site never looks at the return value? Wouldn't it be better to make >> there be no return value in that case? If there is a return value, some >> calling context in the future might take that into account and then the >> lack of a free_irq would be a memory leak. Also if the first request_irq >> can never fail, perhaps that should be made explicit by not testing the >> return value? >> >> julia > This function is an init_call, not a probe function, and it is only > called ONCE. > The dma device here has two interrupts, one IRQ_DMA, another IRQ_DMAERR. > And the device could work without IRQ_DMAERR. > The return value should indicate whether there is something wrong during > initialization, so the function needs return errno when any request_irq > is failed. > For the first request_irq, some code has prepared its resources before > this call, so I suppose it successful. However, the return value must be > tested.
OK, thank you for the explanation. I will change the patch.
julia
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