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-Wshift-count-overflow in drivers/vdpa/mlx5/net/mlx5_vnet.c #1140

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nathanchance opened this issue Aug 21, 2020 · 1 comment
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-Wshift-count-overflow in drivers/vdpa/mlx5/net/mlx5_vnet.c #1140

nathanchance opened this issue Aug 21, 2020 · 1 comment
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@nathanchance
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-Wshift-count-overflow [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 5.9 This bug was fixed in Linux 5.9

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@nathanchance
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Several instances along the lines of:

drivers/vdpa/mlx5/net/mlx5_vnet.c:187:18: warning: shift count >= width of type [-Wshift-count-overflow]
        if (features & ~VALID_FEATURES_MASK)
                        ^~~~~~~~~~~~~~~~~~~
drivers/vdpa/mlx5/net/mlx5_vnet.c:27:60: note: expanded from macro 'VALID_FEATURES_MASK'
         BIT(VIRTIO_NET_F_MQ) | BIT(VIRTIO_NET_F_CTRL_MAC_ADDR) | BIT(VIRTIO_NET_F_HASH_REPORT) |  \
                                                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/vdso/bits.h:7:26: note: expanded from macro 'BIT'
#define BIT(nr)                 (UL(1) << (nr))
                                       ^  ~~~~

Patch submitted: https://lore.kernel.org/r/20200821225018.940798-1-natechancellor@gmail.com
@nathanchance nathanchance added [BUG] linux A bug that should be fixed in the mainline kernel. [PATCH] Submitted A patch has been submitted for review -Wshift-count-overflow labels Aug 21, 2020
@nathanchance nathanchance self-assigned this Aug 21, 2020
fengguang pushed a commit to 0day-ci/linux that referenced this issue Aug 21, 2020
@nathanchance @intel-lab-lkp
vdpa/mlx5: Avoid warnings about shifts on 32-bit platforms
ea61db2 
Clang warns several times when building for 32-bit ARM along the lines
of:

drivers/vdpa/mlx5/net/mlx5_vnet.c:1462:31: warning: shift count >= width
of type [-Wshift-count-overflow]
                ndev->mvdev.mlx_features |= BIT(VIRTIO_F_VERSION_1);
                                            ^~~~~~~~~~~~~~~~~~~~~~~

This is related to the BIT macro, which uses an unsigned long literal,
which is 32-bit on ARM so having a shift equal to or larger than 32 will
cause this warning, such as the above, where VIRTIO_F_VERSION_1 is 32.
To avoid this, use BIT_ULL, which will be an unsigned long long. This
matches the size of the features field throughout this driver, which is
u64 so there should be no functional change.

Fixes: 1a86b37 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
Link: ClangBuiltLinux#1140
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
torvalds pushed a commit to torvalds/linux that referenced this issue Aug 26, 2020
@nathanchance @mstsirkin
vdpa/mlx5: Avoid warnings about shifts on 32-bit platforms
cbb5235 
Clang warns several times when building for 32-bit ARM along the lines
of:

drivers/vdpa/mlx5/net/mlx5_vnet.c:1462:31: warning: shift count >= width
of type [-Wshift-count-overflow]
                ndev->mvdev.mlx_features |= BIT(VIRTIO_F_VERSION_1);
                                            ^~~~~~~~~~~~~~~~~~~~~~~

This is related to the BIT macro, which uses an unsigned long literal,
which is 32-bit on ARM so having a shift equal to or larger than 32 will
cause this warning, such as the above, where VIRTIO_F_VERSION_1 is 32.
To avoid this, use BIT_ULL, which will be an unsigned long long. This
matches the size of the features field throughout this driver, which is
u64 so there should be no functional change.

Fixes: 1a86b37 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
Link: ClangBuiltLinux#1140
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://lore.kernel.org/r/20200821225018.940798-1-natechancellor@gmail.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Acked-by: Eli Cohen <elic@nvidia.com>
@nathanchance
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Merged into mainline: https://git.kernel.org/linus/cbb523594eb718944b726ba52bb43a1d66188a17

@nathanchance nathanchance added [FIXED][LINUX] 5.9 This bug was fixed in Linux 5.9 and removed [PATCH] Submitted A patch has been submitted for review labels Aug 26, 2020
gregmarsden pushed a commit to oracle/linux-uek that referenced this issue Dec 18, 2020
@nathanchance @jfvogel
vdpa/mlx5: Avoid warnings about shifts on 32-bit platforms
395d836 
Clang warns several times when building for 32-bit ARM along the lines
of:

drivers/vdpa/mlx5/net/mlx5_vnet.c:1462:31: warning: shift count >= width
of type [-Wshift-count-overflow]
                ndev->mvdev.mlx_features |= BIT(VIRTIO_F_VERSION_1);
                                            ^~~~~~~~~~~~~~~~~~~~~~~

This is related to the BIT macro, which uses an unsigned long literal,
which is 32-bit on ARM so having a shift equal to or larger than 32 will
cause this warning, such as the above, where VIRTIO_F_VERSION_1 is 32.
To avoid this, use BIT_ULL, which will be an unsigned long long. This
matches the size of the features field throughout this driver, which is
u64 so there should be no functional change.

Fixes: 1a86b37 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
Link: ClangBuiltLinux/linux#1140
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://lore.kernel.org/r/20200821225018.940798-1-natechancellor@gmail.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Acked-by: Eli Cohen <elic@nvidia.com>
(cherry picked from commit cbb5235)

Conflicts:
	drivers/vdpa/mlx5/net/mlx5_vnet.c

Remove virtio feature bits that are absent from UEK:
  VIRTIO_NET_F_RSS
  VIRTIO_NET_F_RSC_EXT
  VIRTIO_NET_F_HASH_REPORT

Orabug: 32121107

Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Qing Huang <qing.huang@oracle.com>
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