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https://bugs.freedesktop.org/show_bug.cgi?id=3217
------- Additional Comments From [EMAIL PROTECTED] 2005-05-21 10:56 -------
Created an attachment (id=2734)
--> (https://bugs.freedesktop.org/attachment.cgi?id=2734&action=view)
patch to fix memory leaks in the PCI consistent memory handling code
Apparently the patch mentioned in comment #10, in addition to breaking the i915
driver on Linux, also introduced a memory leak into the PCI consistent memory
handling code for Linux. There are two problems:
1. drm_pci_alloc() allocates new drm_dma_handle_t structure, but drm_pci_free()
does not free it - this leads to a memory leak in drivers which use
drm_pci_alloc() and drm_pci_free(). (The BSD implementation of drm_pci_free()
_does_ free the drm_dma_handle_t structure passed to it.)
2. drm_addmap() calls drm_pci_alloc(), but does not save the pointer to the
created drm_dma_handle_t structure - instead, it takes the virtual and bus
addresses from it and stores just them; the drm_dma_handle_t structure is
leaked.
The attached patch attempts to fix these problems.
The solution to the first problem is obvious: drm_pci_free() must free the
structure passed to it, so that the Linux and BSD implementation behave in the
same way. The second problem, however, is worse - the code has calls like
drm_pci_free(dev, &dmah);
which would obviously break if drm_pci_free() will free its argument.
The real problem is that the Linux DRM core does not have an OS-specific
drm_local_map_t - therefore there is no place to store the drm_dma_handle_t
pointer from drm_pci_alloc() to pass it to drm_pci_free() later. Introducing
real drm_local_map_t to the Linux DRM core will need major changes, therefore
my patch uses a somewhat hackish approach:
1) drm_addmap() just calls kfree(dmah) on the drm_dma_handle_t pointer from
drm_pci_alloc() to avoid leaking that memory.
2) A new function - __drm_pci_free() - is introduced; this function works just
like drm_pci_free(), but does not free the drm_dma_handle_t structure passed to
it. This function is used instead of drm_pci_free() in places where the
drm_dma_handle_t structure is constructed on the stack. Only the DRM core has
such code, therefore __drm_pci_free() does not need to be exported.
This patch is only compile tested now, like the previous one.
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