Re: [PATCH] ethernet: mlx4: Delete an error message for a failed memory allocation in five functions

From: Tariq Toukan
Date: Wed Jan 03 2018 - 06:25:19 EST




On 03/01/2018 10:06 AM, Julia Lawall wrote:


On Wed, 3 Jan 2018, Tariq Toukan wrote:



On 01/01/2018 10:46 PM, SF Markus Elfring wrote:
From: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
Date: Mon, 1 Jan 2018 21:42:27 +0100

Omit an extra message for a memory allocation failure in these functions.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
---

Is this an issue? Why? What is your motivation?
These are error messages, very informative, appear only upon errors, and in
control flow.

Strings take up space. Since there is a backtrace on an out of memory
problem, if the string does not provide any more information than the
position of the call, then there is not much added value. I don't know
what was the string in this case. If it provides some additional
information, then it would be reasonable to keep it.

I don't really accept this claim...

Short informative strings worth the tiny space they consume. It helps the users of our driver understand what went wrong in simple words, without the need to understand the role of the functions/callstack or being familiar with different parts of the driver code.

In addition, some out-of-memory errors are recoverable, even though their backtrace is also printed. For example, in function mlx4_en_create_cq (appears in patch) we have a first allocation attempt (kzalloc_node) and a fallback (kzalloc). I'd prefer to state a clear error message only when both have failed, because otherwise the user might be confused whether the backtrace should indicate a malfunctioning interface, or not.

Tariq


julia

--
To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html