[Intel-gfx] [PATCH] drm/i915: Break up the large vsnprintf() in print_error_buffers()
Daniel Vetter
daniel at ffwll.ch
Sun Jun 30 01:00:16 CEST 2013
On Sat, Jun 29, 2013 at 11:26:50PM +0100, Chris Wilson wrote:
> So it appears that I have encountered some bogosity when trying to call
> i915_error_printf() with many arguments from print_error_buffers(). The
> symptom is that the vsnprintf parser tries to interpret an integer arg
> as a character string, the resulting OOPS indicating stack corruption.
> Replacing the single call with its 13 format specifiers and arguments
> with multiple calls to i915_error_printf() worked fine. This patch goes
> one step further and introduced i915_error_puts() to pass the strings
> simply.
>
> It may not fix the root cause, but it does prevent my box from dying and
> I think helps make print_error_buffers() more friendly.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=66077
> Cc: Mika Kuoppala <mika.kuoppala at intel.com>
Queued for -next, thanks for the patch.
-Daniel
> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 109 ++++++++++++++++++++++++++----------
> 1 file changed, 79 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 55c89af..7eae6b0 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -650,41 +650,44 @@ static const char *purgeable_flag(int purgeable)
> return purgeable ? " purgeable" : "";
> }
>
> -static void i915_error_vprintf(struct drm_i915_error_state_buf *e,
> - const char *f, va_list args)
> +static bool __i915_error_ok(struct drm_i915_error_state_buf *e)
> {
> - unsigned len;
>
> if (!e->err && WARN(e->bytes > (e->size - 1), "overflow")) {
> e->err = -ENOSPC;
> - return;
> + return false;
> }
>
> if (e->bytes == e->size - 1 || e->err)
> - return;
> + return false;
>
> - /* Seek the first printf which is hits start position */
> - if (e->pos < e->start) {
> - len = vsnprintf(NULL, 0, f, args);
> - if (e->pos + len <= e->start) {
> - e->pos += len;
> - return;
> - }
> + return true;
> +}
>
> - /* First vsnprintf needs to fit in full for memmove*/
> - if (len >= e->size) {
> - e->err = -EIO;
> - return;
> - }
> +static bool __i915_error_seek(struct drm_i915_error_state_buf *e,
> + unsigned len)
> +{
> + if (e->pos + len <= e->start) {
> + e->pos += len;
> + return false;
> }
>
> - len = vsnprintf(e->buf + e->bytes, e->size - e->bytes, f, args);
> - if (len >= e->size - e->bytes)
> - len = e->size - e->bytes - 1;
> + /* First vsnprintf needs to fit in its entirety for memmove */
> + if (len >= e->size) {
> + e->err = -EIO;
> + return false;
> + }
>
> + return true;
> +}
> +
> +static void __i915_error_advance(struct drm_i915_error_state_buf *e,
> + unsigned len)
> +{
> /* If this is first printf in this window, adjust it so that
> * start position matches start of the buffer
> */
> +
> if (e->pos < e->start) {
> const size_t off = e->start - e->pos;
>
> @@ -704,6 +707,51 @@ static void i915_error_vprintf(struct drm_i915_error_state_buf *e,
> e->pos += len;
> }
>
> +static void i915_error_vprintf(struct drm_i915_error_state_buf *e,
> + const char *f, va_list args)
> +{
> + unsigned len;
> +
> + if (!__i915_error_ok(e))
> + return;
> +
> + /* Seek the first printf which is hits start position */
> + if (e->pos < e->start) {
> + len = vsnprintf(NULL, 0, f, args);
> + if (!__i915_error_seek(e, len))
> + return;
> + }
> +
> + len = vsnprintf(e->buf + e->bytes, e->size - e->bytes, f, args);
> + if (len >= e->size - e->bytes)
> + len = e->size - e->bytes - 1;
> +
> + __i915_error_advance(e, len);
> +}
> +
> +static void i915_error_puts(struct drm_i915_error_state_buf *e,
> + const char *str)
> +{
> + unsigned len;
> +
> + if (!__i915_error_ok(e))
> + return;
> +
> + len = strlen(str);
> +
> + /* Seek the first printf which is hits start position */
> + if (e->pos < e->start) {
> + if (!__i915_error_seek(e, len))
> + return;
> + }
> +
> + if (len >= e->size - e->bytes)
> + len = e->size - e->bytes - 1;
> + memcpy(e->buf + e->bytes, str, len);
> +
> + __i915_error_advance(e, len);
> +}
> +
> void i915_error_printf(struct drm_i915_error_state_buf *e, const char *f, ...)
> {
> va_list args;
> @@ -714,6 +762,7 @@ void i915_error_printf(struct drm_i915_error_state_buf *e, const char *f, ...)
> }
>
> #define err_printf(e, ...) i915_error_printf(e, __VA_ARGS__)
> +#define err_puts(e, s) i915_error_puts(e, s)
>
> static void print_error_buffers(struct drm_i915_error_state_buf *m,
> const char *name,
> @@ -723,26 +772,26 @@ static void print_error_buffers(struct drm_i915_error_state_buf *m,
> err_printf(m, "%s [%d]:\n", name, count);
>
> while (count--) {
> - err_printf(m, " %08x %8u %02x %02x %x %x%s%s%s%s%s%s%s",
> + err_printf(m, " %08x %8u %02x %02x %x %x",
> err->gtt_offset,
> err->size,
> err->read_domains,
> err->write_domain,
> - err->rseqno, err->wseqno,
> - pin_flag(err->pinned),
> - tiling_flag(err->tiling),
> - dirty_flag(err->dirty),
> - purgeable_flag(err->purgeable),
> - err->ring != -1 ? " " : "",
> - ring_str(err->ring),
> - cache_level_str(err->cache_level));
> + err->rseqno, err->wseqno);
> + err_puts(m, pin_flag(err->pinned));
> + err_puts(m, tiling_flag(err->tiling));
> + err_puts(m, dirty_flag(err->dirty));
> + err_puts(m, purgeable_flag(err->purgeable));
> + err_puts(m, err->ring != -1 ? " " : "");
> + err_puts(m, ring_str(err->ring));
> + err_puts(m, cache_level_str(err->cache_level));
>
> if (err->name)
> err_printf(m, " (name: %d)", err->name);
> if (err->fence_reg != I915_FENCE_REG_NONE)
> err_printf(m, " (fence: %d)", err->fence_reg);
>
> - err_printf(m, "\n");
> + err_puts(m, "\n");
> err++;
> }
> }
> --
> 1.8.3.1
>
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> Intel-gfx at lists.freedesktop.org
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--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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