linux-kernel - [PATCH 02/20] i915,uaccess: Fix redundant CLAC

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Message-Id: <20190307115159.262970101@infradead.org>
Date:   Thu, 07 Mar 2019 12:45:13 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     torvalds@...ux-foundation.org, tglx@...utronix.de, hpa@...or.com,
        julien.thierry@....com, will.deacon@....com, luto@...capital.net,
        mingo@...nel.org, catalin.marinas@....com, james.morse@....com,
        valentin.schneider@....com, brgerst@...il.com, jpoimboe@...hat.com,
        luto@...nel.org, bp@...en8.de, dvlasenk@...hat.com
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        dvyukov@...gle.com, rostedt@...dmis.org,
        Chris Wilson <chris@...is-wilson.co.uk>
Subject: [PATCH 02/20] i915,uaccess: Fix redundant CLAC

drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x3c: redundant UACCESS disable
drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x66: redundant UACCESS disable

AKA. you don't need user_access_end() if user_access_begin() fails.

Cc: Chris Wilson <chris@...is-wilson.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1606,6 +1606,7 @@ static int eb_copy_relocations(const str
 					     len)) {
 end_user:
 				user_access_end();
+end:
 				kvfree(relocs);
 				err = -EFAULT;
 				goto err;
@@ -1625,7 +1626,7 @@ static int eb_copy_relocations(const str
 		 * relocations were valid.
 		 */
 		if (!user_access_begin(urelocs, size))
-			goto end_user;
+			goto end;
 
 		for (copied = 0; copied < nreloc; copied++)
 			unsafe_put_user(-1,
@@ -2616,7 +2617,7 @@ i915_gem_execbuffer2_ioctl(struct drm_de
 		 * when we did the "copy_from_user()" above.
 		 */
 		if (!user_access_begin(user_exec_list, count * sizeof(*user_exec_list)))
-			goto end_user;
+			goto end;
 
 		for (i = 0; i < args->buffer_count; i++) {
 			if (!(exec2_list[i].offset & UPDATE))
@@ -2630,6 +2631,7 @@ i915_gem_execbuffer2_ioctl(struct drm_de
 		}
 end_user:
 		user_access_end();
+end:;
 	}
 
 	args->flags &= ~__I915_EXEC_UNKNOWN_FLAGS;