* Is iounmap(NULL) safe or not?
@ 2017-05-05 22:50 Alexey Khoroshilov
2017-05-06 7:47 ` Benjamin Herrenschmidt
0 siblings, 1 reply; 2+ messages in thread
From: Alexey Khoroshilov @ 2017-05-05 22:50 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Greg Kroah-Hartman
Cc: Alexey Khoroshilov, linux-mm, linuxppc-dev, linux-kernel, ldv-project
Hello,
It seems thare are many places where code assumes iounmap(NULL) is safe.
Also there are several patches that state it explicitly:
ff6defa6a8fa ("ALSA: Deletion of checks before the function call "iounmap")
e24bb0ed8179 ("staging: dgnc: remove NULL test")
At the same time it seems PPC implementation generates a warning in this case:
3bfafd6b136b ("netxen: avoid invalid iounmap")
arch/powerpc/mm/pgtable_64.c:
if ((unsigned long)addr < ioremap_bot) {
printk(KERN_WARNING "Attempt to iounmap early bolted mapping"
" at 0x%p\n", addr);
return;
}
Could you please clarify if iounmap(NULL) safe or not.
I guess it would be less errorprone if the answer is architecture independent.
--
Thank you,
Alexey Khoroshilov
Linux Verification Center, ISPRAS
web: http://linuxtesting.org
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Is iounmap(NULL) safe or not?
2017-05-05 22:50 Is iounmap(NULL) safe or not? Alexey Khoroshilov
@ 2017-05-06 7:47 ` Benjamin Herrenschmidt
0 siblings, 0 replies; 2+ messages in thread
From: Benjamin Herrenschmidt @ 2017-05-06 7:47 UTC (permalink / raw)
To: Alexey Khoroshilov, Greg Kroah-Hartman
Cc: linux-mm, linuxppc-dev, linux-kernel, ldv-project
On Sat, 2017-05-06 at 01:50 +0300, Alexey Khoroshilov wrote:
> Could you please clarify if iounmap(NULL) safe or not.
> I guess it would be less errorprone if the answer is architecture independent.
I think it's supposed to be and we should fix ppc.
Cheers,
Ben.
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