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-Wunused-value in net/xdp #544

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nathanchance opened this issue Jun 18, 2019 · 5 comments
Closed

-Wunused-value in net/xdp #544

nathanchance opened this issue Jun 18, 2019 · 5 comments
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@nathanchance
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-Wunused-value [ARCH] arm32 This bug impacts ARCH=arm [ARCH] arm64 This bug impacts ARCH=arm64 [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 5.3 This bug was fixed in Linux 5.3

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@nathanchance
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When testing the patch in #520, on either 32-bit or 64-bit ARM:

In file included from net/xdp/xsk_queue.c:10:
net/xdp/xsk_queue.h:292:2: warning: expression result unused [-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.
In file included from net/xdp/xsk_diag.c:14:
net/xdp/xsk_queue.h:292:2: warning: expression result unused [-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.
In file included from net/xdp/xdp_umem.c:19:
net/xdp/xsk_queue.h:292:2: warning: expression result unused [-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.
In file included from net/xdp/xsk.c:28:
net/xdp/xsk_queue.h:292:2: warning: expression result unused [-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.

Also reported by @tmroeder on that same thread.

Can be reproduced with make -j$(nproc) CC=clang allyesconfig net/xdp/
@nathanchance nathanchance added [BUG] linux A bug that should be fixed in the mainline kernel. [ARCH] arm64 This bug impacts ARCH=arm64 [ARCH] arm32 This bug impacts ARCH=arm -Wunused-value labels Jun 18, 2019
@nathanchance
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This is now visible in -next for everyone because -Wunused-value has been turned on.

@nathanchance nathanchance assigned nathanchance and unassigned nhukc Jun 25, 2019
@nathanchance
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I've found the issue and am about to send a fix.

@nathanchance
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Patch sent: https://lore.kernel.org/lkml/20190625182352.13918-1-natechancellor@gmail.com/

igsilya pushed a commit to igsilya/linux that referenced this issue Jun 26, 2019
@nathanchance @borkmann
xsk: Properly terminate assignment in xskq_produce_flush_desc
f7019b7 
Clang warns:

In file included from net/xdp/xsk_queue.c:10:
net/xdp/xsk_queue.h:292:2: warning: expression result unused
[-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.

The q->prod_tail assignment has a comma at the end, not a semi-colon.
Fix that so clang no longer warns and everything works as expected.

Fixes: c497176 ("xsk: add Rx receive functions and poll support")
Link: ClangBuiltLinux#544
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
@nathanchance
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Patch accepted: https://git.kernel.org/bpf/bpf/c/f7019b7b0ad14bde732b8953161994edfc384953

@nathanchance nathanchance added the [PATCH] Accepted A submitted patch has been accepted upstream label Jun 26, 2019
@nathanchance
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Merged into mainline: https://git.kernel.org/torvalds/c/f7019b7b0ad14bde732b8953161994edfc384953

@nathanchance nathanchance added [FIXED][LINUX] 5.3 This bug was fixed in Linux 5.3 and removed [PATCH] Accepted A submitted patch has been accepted upstream labels Jul 11, 2019
mrchapp pushed a commit to mrchapp/linux that referenced this issue Jul 24, 2019
@nathanchance @gregkh
xsk: Properly terminate assignment in xskq_produce_flush_desc
3d74ff0 
[ Upstream commit f7019b7 ]

Clang warns:

In file included from net/xdp/xsk_queue.c:10:
net/xdp/xsk_queue.h:292:2: warning: expression result unused
[-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.

The q->prod_tail assignment has a comma at the end, not a semi-colon.
Fix that so clang no longer warns and everything works as expected.

Fixes: c497176 ("xsk: add Rx receive functions and poll support")
Link: ClangBuiltLinux#544
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
mrchapp pushed a commit to mrchapp/linux that referenced this issue Jul 24, 2019
@nathanchance @gregkh
xsk: Properly terminate assignment in xskq_produce_flush_desc
1937240 
[ Upstream commit f7019b7 ]

Clang warns:

In file included from net/xdp/xsk_queue.c:10:
net/xdp/xsk_queue.h:292:2: warning: expression result unused
[-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.

The q->prod_tail assignment has a comma at the end, not a semi-colon.
Fix that so clang no longer warns and everything works as expected.

Fixes: c497176 ("xsk: add Rx receive functions and poll support")
Link: ClangBuiltLinux#544
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
mrchapp pushed a commit to mrchapp/linux that referenced this issue Jul 25, 2019
@nathanchance @gregkh
xsk: Properly terminate assignment in xskq_produce_flush_desc
9d7d1bf 
[ Upstream commit f7019b7 ]

Clang warns:

In file included from net/xdp/xsk_queue.c:10:
net/xdp/xsk_queue.h:292:2: warning: expression result unused
[-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.

The q->prod_tail assignment has a comma at the end, not a semi-colon.
Fix that so clang no longer warns and everything works as expected.

Fixes: c497176 ("xsk: add Rx receive functions and poll support")
Link: ClangBuiltLinux#544
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
mrchapp pushed a commit to mrchapp/linux that referenced this issue Jul 25, 2019
@nathanchance @gregkh
xsk: Properly terminate assignment in xskq_produce_flush_desc
f767032 
[ Upstream commit f7019b7 ]

Clang warns:

In file included from net/xdp/xsk_queue.c:10:
net/xdp/xsk_queue.h:292:2: warning: expression result unused
[-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.

The q->prod_tail assignment has a comma at the end, not a semi-colon.
Fix that so clang no longer warns and everything works as expected.

Fixes: c497176 ("xsk: add Rx receive functions and poll support")
Link: ClangBuiltLinux#544
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
woodsts pushed a commit to woodsts/linux-stable that referenced this issue Jul 26, 2019
@nathanchance @gregkh
xsk: Properly terminate assignment in xskq_produce_flush_desc
eeb491b 
[ Upstream commit f7019b7 ]

Clang warns:

In file included from net/xdp/xsk_queue.c:10:
net/xdp/xsk_queue.h:292:2: warning: expression result unused
[-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.

The q->prod_tail assignment has a comma at the end, not a semi-colon.
Fix that so clang no longer warns and everything works as expected.

Fixes: c497176 ("xsk: add Rx receive functions and poll support")
Link: ClangBuiltLinux/linux#544
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
woodsts pushed a commit to woodsts/linux-stable that referenced this issue Jul 26, 2019
@nathanchance @gregkh
xsk: Properly terminate assignment in xskq_produce_flush_desc
b02beb2 
[ Upstream commit f7019b7 ]

Clang warns:

In file included from net/xdp/xsk_queue.c:10:
net/xdp/xsk_queue.h:292:2: warning: expression result unused
[-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.

The q->prod_tail assignment has a comma at the end, not a semi-colon.
Fix that so clang no longer warns and everything works as expected.

Fixes: c497176 ("xsk: add Rx receive functions and poll support")
Link: ClangBuiltLinux/linux#544
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Whissi pushed a commit to Whissi/linux-stable that referenced this issue Jul 26, 2019
@nathanchance @gregkh
xsk: Properly terminate assignment in xskq_produce_flush_desc
dad0b17 
[ Upstream commit f7019b7 ]

Clang warns:

In file included from net/xdp/xsk_queue.c:10:
net/xdp/xsk_queue.h:292:2: warning: expression result unused
[-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.

The q->prod_tail assignment has a comma at the end, not a semi-colon.
Fix that so clang no longer warns and everything works as expected.

Fixes: c497176 ("xsk: add Rx receive functions and poll support")
Link: ClangBuiltLinux/linux#544
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
isjerryxiao pushed a commit to isjerryxiao/Amlogic_s905-kernel that referenced this issue Jul 29, 2019
@nathanchance @isjerryxiao
xsk: Properly terminate assignment in xskq_produce_flush_desc
c99ced4 
[ Upstream commit f7019b7b0ad14bde732b8953161994edfc384953 ]

Clang warns:

In file included from net/xdp/xsk_queue.c:10:
net/xdp/xsk_queue.h:292:2: warning: expression result unused
[-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.

The q->prod_tail assignment has a comma at the end, not a semi-colon.
Fix that so clang no longer warns and everything works as expected.

Fixes: c497176 ("xsk: add Rx receive functions and poll support")
Link: ClangBuiltLinux/linux#544
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Staars pushed a commit to Staars/linux-stable that referenced this issue Aug 1, 2019
@nathanchance @Staars
xsk: Properly terminate assignment in xskq_produce_flush_desc
746d88f 
[ Upstream commit f7019b7b0ad14bde732b8953161994edfc384953 ]

Clang warns:

In file included from net/xdp/xsk_queue.c:10:
net/xdp/xsk_queue.h:292:2: warning: expression result unused
[-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.

The q->prod_tail assignment has a comma at the end, not a semi-colon.
Fix that so clang no longer warns and everything works as expected.

Fixes: c497176 ("xsk: add Rx receive functions and poll support")
Link: ClangBuiltLinux/linux#544
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
dsd pushed a commit to endlessm/linux that referenced this issue Aug 12, 2019
@nathanchance
xsk: Properly terminate assignment in xskq_produce_flush_desc
f8a10bd 
BugLink: https://bugs.launchpad.net/bugs/1838089

[ Upstream commit f7019b7 ]

Clang warns:

In file included from net/xdp/xsk_queue.c:10:
net/xdp/xsk_queue.h:292:2: warning: expression result unused
[-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.

The q->prod_tail assignment has a comma at the end, not a semi-colon.
Fix that so clang no longer warns and everything works as expected.

Fixes: c497176 ("xsk: add Rx receive functions and poll support")
Link: ClangBuiltLinux/linux#544
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
jpuhlman pushed a commit to MontaVista-OpenSourceTechnology/linux-mvista-2.6 that referenced this issue Aug 15, 2019
@nathanchance @mvakuster
xsk: Properly terminate assignment in xskq_produce_flush_desc
aded66b 
Source: Kernel.org
MR: 99311
Type: Integration
Disposition: Backport from git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable  linux-4.19.y
ChangeID: dad0b17e4a4e68df83e2904034e76a94c0a82d91
Description:

[ Upstream commit f7019b7b0ad14bde732b8953161994edfc384953 ]

Clang warns:

In file included from net/xdp/xsk_queue.c:10:
net/xdp/xsk_queue.h:292:2: warning: expression result unused
[-Wunused-value]
        WRITE_ONCE(q->ring->producer, q->prod_tail);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:284:6: note: expanded from macro 'WRITE_ONCE'
        __u.__val;                                      \
        ~~~ ^~~~~
1 warning generated.

The q->prod_tail assignment has a comma at the end, not a semi-colon.
Fix that so clang no longer warns and everything works as expected.

Fixes: c497176 ("xsk: add Rx receive functions and poll support")
Link: ClangBuiltLinux/linux#544
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Armin Kuster <akuster@mvista.com>
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@nathanchance nathanchance

Labels
-Wunused-value [ARCH] arm32 This bug impacts ARCH=arm [ARCH] arm64 This bug impacts ARCH=arm64 [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 5.3 This bug was fixed in Linux 5.3
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@nickdesaulniers @nathanchance @nhukc