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* [Intel-gfx] [PATCH] [i915] avoid infinite retries in GuC/HuC loading
@ 2023-03-12 19:56 Alexandre Oliva
  2023-03-20 23:15 ` [Intel-gfx] ✗ Fi.CI.BUILD: warning for " Patchwork
                   ` (5 more replies)
  0 siblings, 6 replies; 11+ messages in thread
From: Alexandre Oliva @ 2023-03-12 19:56 UTC (permalink / raw)
  To: intel-gfx; +Cc: stable


If two or more suitable entries with the same filename are found in
__uc_fw_auto_select's fw_blobs, and that filename fails to load in the
first attempt and in the retry, when __uc_fw_auto_select is called for
the third time, the coincidence of strings will cause it to clear
file_selected.path at the first hit, so it will return the second hit
over and over again, indefinitely.

Of course this doesn't occur with the pristine blob lists, but a
modified version could run into this, e.g., patching in a duplicate
entry, or (as in our case) disarming blob loading by remapping their
names to "/*(DEBLOBBED)*/", given a toolchain that unifies identical
string literals.

Of course I'm ready to carry a patchlet to avoid this problem
triggered by our (GNU Linux-libre's) intentional changes, but I
figured you might be interested in fail-safing it even in accidental
backporting circumstances.  I realize it's not entirely foolproof: if
the same string appears in two entries separated by a different one,
the infinite loop might still occur.  Catching that even more unlikely
situation seemed too expensive.

Link: https://www.fsfla.org/pipermail/linux-libre/2023-March/003506.html
Cc: intel-gfx@lists.freedesktop.org
Cc: stable@vger.kernel.org # 6.[12].x
Signed-off-by: Alexandre Oliva <lxoliva@fsfla.org>
---
 drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
index 9d6f571097e6..2b7564a3ed82 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
@@ -259,7 +259,10 @@ __uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
 				uc_fw->file_selected.path = NULL;
 
 			continue;
-		}
+		} else if (uc_fw->file_wanted.path == blob->path)
+			/* Avoid retrying forever when neighbor
+			   entries point to the same path.  */
+			continue;
 
 		uc_fw->file_selected.path = blob->path;
 		uc_fw->file_wanted.path = blob->path;
-- 
2.25.1


-- 
Alexandre Oliva, happy hacker                https://FSFLA.org/blogs/lxo/
   Free Software Activist                       GNU Toolchain Engineer
Disinformation flourishes because many people care deeply about injustice
but very few check the facts.  Ask me about <https://stallmansupport.org>

^ permalink raw reply related	[flat|nested] 11+ messages in thread
end of thread, other threads:[~2023-04-02 20:43 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-03-12 19:56 [Intel-gfx] [PATCH] [i915] avoid infinite retries in GuC/HuC loading Alexandre Oliva
2023-03-20 23:15 ` [Intel-gfx] ✗ Fi.CI.BUILD: warning for " Patchwork
2023-03-20 23:15 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: " Patchwork
2023-03-20 23:33 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2023-03-21  3:55 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork
2023-03-22 20:48 ` [Intel-gfx] [PATCH] [i915] " Rodrigo Vivi
2023-03-23  1:30   ` Alexandre Oliva
2023-03-24 18:45 ` John Harrison
2023-03-26  9:46   ` Alexandre Oliva
2023-03-31 19:14     ` John Harrison
2023-04-02 20:42       ` Alexandre Oliva

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