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SubjectRe: kmemleak hexdump proposal
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Date
Hi,

On Mon, 2009-06-29 at 21:10 +0100, Sergey Senozhatsky wrote:
> This is actually draft. We'll discuss details during next merge window (or earlier).

Better earlier (I plan to get some more kmemleak patches into
linux-next).

> hex dump prints not more than HEX_MAX_LINES lines by HEX_ROW_SIZE (16 or 32) bytes.
> ( min(object->size, HEX_MAX_LINES * HEX_ROW_SIZE) ).
>
> Example (HEX_ROW_SIZE 16):
>
> unreferenced object 0xf68b59b8 (size 32):
> comm "swapper", pid 1, jiffies 4294877610
> hex dump (first 32 bytes):
> 70 6e 70 20 30 30 3a 30 31 00 5a 5a 5a 5a 5a 5a pnp 00:01.ZZZZZZ
> 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a a5 ZZZZZZZZZZZZZZZ.

That's my preferred as I do not want to go beyond column 80.

> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
> index 5063873..65c5d74 100644
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -160,6 +160,15 @@ struct kmemleak_object {
> /* flag set to not scan the object */
> #define OBJECT_NO_SCAN (1 << 2)
>
> +/* number of bytes to print per line; must be 16 or 32 */
> +#define HEX_ROW_SIZE 32

16 here.

> +/* number of bytes to print at a time (1, 2, 4, 8) */
> +#define HEX_GROUP_SIZE 1
> +/* include ASCII after the hex output */
> +#define HEX_ASCII 1
> +/* max number of lines to be printed */
> +#define HEX_MAX_LINES 2
> +
> /* the list of all allocated objects */
> static LIST_HEAD(object_list);
> /* the list of gray-colored objects (see color_gray comment below) */
> @@ -181,6 +190,8 @@ static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
> static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
> /* set if a fata kmemleak error has occurred */
> static atomic_t kmemleak_error = ATOMIC_INIT(0);
> +/* set if hex dump should be printed */
> +static atomic_t kmemleak_hex_dump = ATOMIC_INIT(1);
[...]
> @@ -303,6 +343,11 @@ static void print_unreferenced(struct seq_file *seq,
> object->pointer, object->size);
> seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu\n",
> object->comm, object->pid, object->jiffies);
> +
> + /* check whether hex dump should be printed */
> + if (atomic_read(&kmemleak_hex_dump))
> + hex_dump_object(seq, object);

No need for this check, just leave it in all cases (as we now only read
the reports via the debug/kmemleak file.

> @@ -1269,6 +1314,10 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
> start_scan_thread();
> else if (strncmp(buf, "scan=off", 8) == 0)
> stop_scan_thread();
> + else if (strncmp(buf, "hexdump=on", 10) == 0)
> + atomic_set(&kmemleak_hex_dump, 1);
> + else if (strncmp(buf, "hexdump=off", 11) == 0)
> + atomic_set(&kmemleak_hex_dump, 0);

Same here.

Thanks.

--
Catalin



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