linux-kernel - [PATCH 2/2] drm/i915: Fix incorrect error handling in shmem

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Message-ID: <20250811093050.38930-2-chentaotao@didiglobal.com>
Date: Mon, 11 Aug 2025 09:31:00 +0000
From: 陈涛涛 Taotao Chen <chentaotao@...iglobal.com>
To: "jani.nikula@...ux.intel.com" <jani.nikula@...ux.intel.com>,
	"joonas.lahtinen@...ux.intel.com" <joonas.lahtinen@...ux.intel.com>,
	"rodrigo.vivi@...el.com" <rodrigo.vivi@...el.com>, "tursulin@...ulin.net"
	<tursulin@...ulin.net>, "airlied@...il.com" <airlied@...il.com>,
	"simona@...ll.ch" <simona@...ll.ch>
CC: "oe-lkp@...ts.linux.dev" <oe-lkp@...ts.linux.dev>, "lkp@...el.com"
	<lkp@...el.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "intel-gfx@...ts.freedesktop.org"
	<intel-gfx@...ts.freedesktop.org>, "brauner@...nel.org" <brauner@...nel.org>,
	"oliver.sang@...el.com" <oliver.sang@...el.com>,
	陈涛涛 Taotao Chen <chentaotao@...iglobal.com>
Subject: [PATCH 2/2] drm/i915: Fix incorrect error handling in shmem_pwrite()

From: Taotao Chen <chentaotao@...iglobal.com>

shmem_pwrite() currently checks for short writes before negative error
codes, which can overwrite real errors (e.g., -EFBIG) with -EIO.
Reorder the checks to return negative errors first, then handle short
writes.

Fixes: 048832a3f400 ("drm/i915: Refactor shmem_pwrite() to use kiocb and write_iter")
Signed-off-by: Taotao Chen <chentaotao@...iglobal.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
index 2b53aad915f5..702532eef207 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -441,12 +441,12 @@ shmem_pwrite(struct drm_i915_gem_object *obj,
 	written = file->f_op->write_iter(&kiocb, &iter);
 	BUG_ON(written == -EIOCBQUEUED);
 
-	if (written != size)
-		return -EIO;
-
 	if (written < 0)
 		return written;
 
+	if (written != size)
+		return -EIO;
+
 	return 0;
 }
 
-- 
2.34.1