On Fri, Sep 04, 2015 at 10:03:46PM -0600, Stephen Warren wrote: > From: Stephen Warren <swar...@nvidia.com> > > DFU currently allocates buffer memory at the start of each data transfer > operation and frees it at the end. Especially since memalign() is used to > allocate the buffer, and various other allocations happen during the > transfer, this can expose the code to heap fragmentation, which prevents > the allocation from succeeding on subsequent transfers. > > Fix the code to allocate the buffer once when DFU mode is initialized, > and free the buffer once when DFU mode is exited, to reduce the exposure > to heap fragmentation. > > The failure mode is: > > // Internally to memalign(), this allocates a lot more than s to guarantee > // that alignment can occur, then returns chunks of memory at the start/ > // end of the allocated buffer to the heap. > p = memalign(a, s); > // Various other malloc()s occur here, some of which allocate the RAM > // immediately before/after "p". > // > // DFU transfer is complete, so buffer is released. > free(p); > // By chance, no other malloc()/free() here, in DFU at least. > // > // A new DFU transfer starts, so the buffer is allocated again. > // In theory this should succeed since we just free()d a buffer of the > // same size. However, this fails because memalign() internally attempts > // to allocate much more than "s", yet free(p) above only free()d a > // little more than "s". > p = memalign(a, s); > > Signed-off-by: Stephen Warren <swar...@nvidia.com> > Acked-by: Lukasz Majewski <l.majew...@samsung.com> > Tested-by: Lukasz Majewski <l.majew...@samsung.com>
Applied to u-boot/master, thanks! -- Tom
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