Messages in this thread | | | Date | Mon, 3 Oct 2005 15:43:50 +0300 | From | Pekka Enberg <> | Subject | Re: [PATCH] release_resource() check for NULL resource |
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On 10/3/05, Russell King <rmk+lkml@arm.linux.org.uk> wrote: > It makes sense for kfree() to ignore NULL pointers, but does it really > make sense for *_unregister() to do so too? Surely you want to only > unregister things which you know have previously been registered?
Usually yes but it makes releasing partial initialization much simpler because you can reuse the normal release counterpart. For example,
static int driver_init(void) { dev->resource1 = request_region(...); if (!dev->resource1) goto failed;
dev->resource2 = request_region(...); if (!dev->resource2) goto failed;
return 0;
failed: driver_release(dev); return -1; }
static void driver_release(struct device * dev) { release_resource(dev->resource1); release_resource(dev->resource2); kfree(dev); }
Many drivers have the release function copy-pasted to init with lots of goto labels exactly because release_region, iounmap, and friends aren't NULL safe.
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