On Thu, 2020-07-30 at 12:44 -0400, Jim Quinlan wrote: > On Wed, Jul 29, 2020 at 10:28 AM Rob Herring <robh+dt@xxxxxxxxxx> wrote: > > On Wed, Jul 29, 2020 at 12:19 AM Christoph Hellwig <hch@xxxxxx> wrote: > > > On Tue, Jul 28, 2020 at 02:24:51PM -0400, Jim Quinlan wrote: > > > > I started using devm_kcalloc() but at least two reviewers convinced me > > > > to just use kcalloc(). In addition, when I was using devm_kcalloc() > > > > it was awkward because 'dev' is not available to this function. > > > > > > > > It comes down to whether unbind/binding the device N times is actually > > > > a reasonable usage. As for my experience I've seen two cases: (1) my > > > > overnight "bind/unbind the PCIe RC driver" script, and we have a > > > > customer who does an unbind/bind as a hail mary to bring back life to > > > > their dead EP device. If the latter case happens repeatedly, there > > > > are bigger problems. > > > > > > We can't just leak the allocations. Do you have a pointer to the > > > arguments against managed resources? I'm generally not a huge fan > > > of the managed resources, but for a case like this they actually seem > > > useful. If we don't use the managed resources we'll at leat need > > > to explicitly free the resources when freeing the device. > > > > The lifetime for devm_kcalloc may not be what we want here. devm > > allocs are freed on probe fail or remove, not on freeing the device > > (there is a just in case free there too though). > > What do you suggest doing as an alternative? I haven't given the idea much thought, but how about using a kref in the first element of your bus_dma_region array. It should be increased upon assigning it to a device and decreased it upon destroying it (triggering the free once it hits 0). It would take care of this memory leak, but also useful where you're sharing bus_dma_regions between devices. Regards, Nicolas _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
