[Mesa-dev] [PATCH 0/2] Simple Klocwork patches

[Juha-Pekka Heikkilä]

Hi Iago,

I know there are lot of places where there is malloc unchecked still
-- and then there is ralloc which is a story of its own. Reason why I
think checking these would be remotely useful in windows only (or
other way around, not under linux kernel) is on Windows one can get
the null pointer from malloc. On Androids I think memory over
committing has always been enabled and on Linux I suspect I belong to
the minority who like to set ulimits for memory.

I agree checking these mostly is quite useless but there are those
corners where it may suddenly become valuable. When process is running
and everything has settled it will be weird if hit any of these checks
but any code which is run when process is starting I notice is the
place where things will fail if they fail. This is of course just my
opinion about the value of these checks but I really dislike
possibility of segfault when it is coming from a library.

I didn't quickly notice where _mesa_error() get more heap. Stack it of
course needs but when I did stress test these _mesa_error() did still
work. Cannot promise my test was 100% correct though, I think it was
over year ago when I was playing with it.

/Juha-Pekka

On Wed, Feb 3, 2016 at 5:12 PM, Iago Toral <itoral at igalia.com> wrote:
> Hi Juha,
>
> I don't know why checking for this might be more relevant in Windows,
> but in any case:
>
> There are a ton of other places in mesa where we allocate memory via
> calloc/malloc and we don't check that the allocation actually succeeded
> so I am not sure that fixing a couple of instances of *small*
> allocations changes anything.
>
> IMHO, this kind of things are only really useful when allocating memory
> for large amounts of data, otherwise even if you check for a NULL
> allocation you still need to make sure that you don't need any extra
> memory to handle that situation, and _mesa_error() needs memory, so it
> is probably not really giving us anything in practice other than
> silencing Klocwork...
>
> Iago
>
> On Wed, 2016-02-03 at 10:56 +0200, Juha-Pekka Heikkila wrote:
>> I'm thinking these things maybe could be wrapped up inside something like
>> "#ifdef windows" or so in the future. At least for Android and Linux these
>> are normally quite useless.
>>
>> /Juha-Pekka
>>
>> Juha-Pekka Heikkila (2):
>>   i965: in brw_link_shader() react to low memory
>>   glsl: Check for null pointer at ir_variable_refcount_visitor()
>>
>>  src/compiler/glsl/ir_variable_refcount.cpp | 7 +++++++
>>  src/mesa/drivers/dri/i965/brw_link.cpp     | 4 ++++
>>  src/mesa/main/ff_fragment_shader.cpp       | 6 ++++--
>>  3 files changed, 15 insertions(+), 2 deletions(-)
>>
>
>