linux-kernel - Why does test_bit() take a volatile addr?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 16 Sep 2013 13:38:35 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	<torvalds@...ux-foundation.org>
Cc:	"LKML" <linux-kernel@...r.kernel.org>
Subject: Why does test_bit() take a volatile addr?

Predates git, does anyone remember the rationale?

ie:
        int test_bit(int nr, const volatile unsigned long *addr)

I noticed because gcc failed to elimiate some code in a patch I was
playing with.

I'm nervous about subtle bugs involved in ripping it out, even if noone
knows why.  Should I add __test_bit()?

Thanks,
Rusty.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/