[PATCH RESEND 6/6] clk: s5p-g2d: Fix incorrect usage of IS_ERR_OR_NULL
From: Tony Prisk <hidden>
Date: 2013-01-02 05:31:53
Also in:
kernel-janitors, linux-media, lkml
On Wed, 2013-01-02 at 08:10 +0300, Dan Carpenter wrote:
clk_get() returns NULL if CONFIG_HAVE_CLK is disabled. I told Tony about this but everyone has been gone with end of year holidays so it hasn't been addressed. Tony, please fix it so people don't apply these patches until clk_get() is updated to not return NULL. It sucks to have to revert patches. regards, dan carpenter
I posted the query to Mike Turquette, linux-kernel and linux-arm-kernel mailing lists, regarding the return of NULL when HAVE_CLK is undefined. Short Answer: A return value of NULL is valid and not an error therefore we should be using IS_ERR, not IS_ERR_OR_NULL on clk_get results. I see the obvious problem this creates, and asked this question: If the driver can't operate with a NULL clk, it should use a IS_ERR_OR_NULL test to test for failure, rather than IS_ERR. And Russell's answer: Why should a _consumer_ of a clock care? It is _very_ important that people get this idea - to a consumer, the struct clk is just an opaque cookie. The fact that it appears to be a pointer does _not_ mean that the driver can do any kind of dereferencing on that pointer - it should never do so. Thread can be viewed here: https://lkml.org/lkml/2012/12/20/105 Regards Tony Prisk