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[Qemu-devel] Re: [PATCH 08/15] blkdebug: fix enum comparison
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] Re: [PATCH 08/15] blkdebug: fix enum comparison |
Date: |
Sun, 5 Sep 2010 20:57:35 +0300 |
User-agent: |
Mutt/1.5.20 (2009-12-10) |
On Sun, Sep 05, 2010 at 03:06:32PM +0000, Blue Swirl wrote:
> The signedness of enum types depend on the compiler implementation.
> Therefore the check for negative values may or may not be meaningful.
>
> Fix by explicitly casting to a signed integer.
>
> Since the values are also checked earlier against event_names
> table, this is an internal error. Change the 'if' to 'assert'.
>
> This also fixes a warning with GCC flag -Wtype-limits.
>
> Signed-off-by: Blue Swirl <address@hidden>
> ---
> block/blkdebug.c | 4 +---
> 1 files changed, 1 insertions(+), 3 deletions(-)
>
> diff --git a/block/blkdebug.c b/block/blkdebug.c
> index 2a63df9..4d6ff0a 100644
> --- a/block/blkdebug.c
> +++ b/block/blkdebug.c
> @@ -439,9 +439,7 @@ static void blkdebug_debug_event(BlockDriverState
> *bs, BlkDebugEvent event)
> struct BlkdebugRule *rule;
> BlkdebugVars old_vars = s->vars;
>
> - if (event < 0 || event >= BLKDBG_EVENT_MAX) {
> - return;
> - }
> + assert((int)event >= 0 && event < BLKDBG_EVENT_MAX);
I am not sure all compilers must generate a negative value from
a very large unsigned integer cast to int.
assert((unsigned)event < BLKDBG_EVENT_MAX);
will do the same but without integer overflow.
>
> QLIST_FOREACH(rule, &s->rules[event], next) {
> process_rule(bs, rule, &old_vars);
> --
> 1.6.2.4