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Re: [Qemu-devel] [PATCH] Error check find_ram_offset
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH] Error check find_ram_offset |
Date: |
Mon, 31 Oct 2011 16:42:15 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) |
Alex Williamson <address@hidden> writes:
> Spotted via code review, we initialize offset to 0 to avoid a
> compiler warning, but in the unlikely case that offset is
> never set to something else, we should abort instead of return
> a value that will almost certainly cause problems.
Compiler warning pointed to the problem until commit 09d7ae90 "Fix
warning about uninitialized variable" papered over it.
> Signed-off-by: Alex Williamson <address@hidden>
> ---
>
> exec.c | 11 +++++++++--
> 1 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/exec.c b/exec.c
> index 9dc4edb..70f6fb8 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -2874,7 +2874,7 @@ static void *file_ram_alloc(RAMBlock *block,
> static ram_addr_t find_ram_offset(ram_addr_t size)
> {
> RAMBlock *block, *next_block;
> - ram_addr_t offset = 0, mingap = RAM_ADDR_MAX;
> + ram_addr_t offset = RAM_ADDR_MAX, mingap = RAM_ADDR_MAX;
>
> if (QLIST_EMPTY(&ram_list.blocks))
> return 0;
> @@ -2890,10 +2890,17 @@ static ram_addr_t find_ram_offset(ram_addr_t size)
> }
> }
> if (next - end >= size && next - end < mingap) {
> - offset = end;
> + offset = end;
> mingap = next - end;
> }
> }
> +
> + if (offset == RAM_ADDR_MAX) {
> + fprintf(stderr, "Failed to find gap of requested size: %" PRIu64
> "\n",
> + (uint64_t)size);
> + abort();
> + }
> +
> return offset;
> }
The loop can't yield offset RAM_ADDR_MAX, because size needs to be zero
for next - end >= size to succeed, and that's not possible.
Reviewed-by: Markus Armbruster <address@hidden>