Re: [PATCH v2] s390/raw3270: Handle memory allocation failures in raw3270_setup_console()

Markus Elfring
2024-06-25T08:12:54Z

> … Thus add corresponding return value checks.

I suggest to move this sentence into a subsequent text line.

> The allocated each memory areas are immediately overwritten by the called
> function zero-initialisation be omitted by calling the "kmalloc" instead.

It seems that you stumbled on wording difficulties according to my previous
patch review suggestion.
I find the intended change more appropriate for another update step.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.10-rc5#n168

> After "ccw_device_enable_console" succeeds, set the bit raw3270 flag to
> RAW3270_FLAGS_CONSOLE.

Why do you find such an adjustment relevant here?

> Fixes: 33403dcfcdfd ("[S390] 3270 console: convert from bootmem to slab")
> Cc: linux-s390@vger.kernel.org

Would you like to specify a “stable tag”?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/stable-kernel-rules.rst?h=v6.10-rc5#n34

> ---

I would appreciate a version description behind the marker line.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.10-rc5#n713

…
> +++ b/drivers/s390/char/raw3270.c
> @@ -811,18 +811,28 @@ struct raw3270 __init *raw3270_setup_console(void)
> if (IS_ERR(cdev))
> return ERR_CAST(cdev);
>
> - rp = kzalloc(sizeof(*rp), GFP_KERNEL | GFP_DMA);
> - ascebc = kzalloc(256, GFP_KERNEL);
> + rp = kmalloc(sizeof(*rp), GFP_KERNEL | GFP_DMA);
> + if (!rp)
> + return ERR_PTR(-ENOMEM);
> + ascebc = kmalloc(256, GFP_KERNEL);
> + if (!ascebc) {
> + kfree(rp);
> + return ERR_PTR(-ENOMEM);
> + }
> rc = raw3270_setup_device(cdev, rp, ascebc);
> - if (rc)
> + if (rc) {
> + kfree(ascebc);
> + kfree(rp);
> return ERR_PTR(rc);
…

Please take further software design options better into account.

A) goto chain
https://wiki.sei.cmu.edu/confluence/display/c/MEM12-C.+Consider+using+a+goto+chain+when+leaving+a+function+on+error+when+using+and+releasing+resources

B) scope-based resource management
https://elixir.bootlin.com/linux/v6.10-rc5/source/include/linux/slab.h#L282

Regards,
Markus