| Message ID | 20230718-nsecs_to_jiffies_timeout-constant-logical-operand-v1-0-36ed8fc8faea@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Avoid -Wconstant-logical-operand in nsecs_to_jiffies_timeout() | expand |
On 7/18/23 18:44, Nathan Chancellor wrote: > Hi all, > > A proposed update to clang's -Wconstant-logical-operand [1] to warn when > the left hand side is a constant as well now triggers with the modulo > expression in nsecs_to_jiffies_timeout() when NSEC_PER_SEC is not a > multiple of HZ, such as CONFIG_HZ=300: > > drivers/gpu/drm/i915/gem/i915_gem_wait.c:189:24: warning: use of logical '&&' with constant operand [-Wconstant-logical-operand] > 189 | if (NSEC_PER_SEC % HZ && > | ~~~~~~~~~~~~~~~~~ ^ > drivers/gpu/drm/i915/gem/i915_gem_wait.c:189:24: note: use '&' for a bitwise operation > 189 | if (NSEC_PER_SEC % HZ && > | ^~ > | & > drivers/gpu/drm/i915/gem/i915_gem_wait.c:189:24: note: remove constant to silence this warning > 1 warning generated. > > In file included from drivers/gpu/drm/v3d/v3d_debugfs.c:12: > drivers/gpu/drm/v3d/v3d_drv.h:343:24: warning: use of logical '&&' with constant operand [-Wconstant-logical-operand] > 343 | if (NSEC_PER_SEC % HZ && > | ~~~~~~~~~~~~~~~~~ ^ > drivers/gpu/drm/v3d/v3d_drv.h:343:24: note: use '&' for a bitwise operation > 343 | if (NSEC_PER_SEC % HZ && > | ^~ > | & > drivers/gpu/drm/v3d/v3d_drv.h:343:24: note: remove constant to silence this warning > 1 warning generated. > > These patches add an explicit comparison to zero to make the > expression a boolean, which clears up the warning. > > The patches have no real dependency on each other but I felt like they > made send together since it is the same code. > > If these could go into mainline sooner rather than later to avoid > breaking builds that can hit this with CONFIG_WERROR, that would be > nice, but I won't insist since I don't think our own CI has builds that > has those conditions, but others might. > > --- > Nathan Chancellor (2): > drm/v3d: Avoid -Wconstant-logical-operand in nsecs_to_jiffies_timeout() > drm/i915: Avoid -Wconstant-logical-operand in nsecs_to_jiffies_timeout() Applied both patches to drm-misc/drm-misc-next! Best Regards, - Maíra > > drivers/gpu/drm/i915/gem/i915_gem_wait.c | 2 +- > drivers/gpu/drm/v3d/v3d_drv.h | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > --- > base-commit: fdf0eaf11452d72945af31804e2a1048ee1b574c > change-id: 20230718-nsecs_to_jiffies_timeout-constant-logical-operand-4a944690f3e9 > > Best regards,
Hi all, A proposed update to clang's -Wconstant-logical-operand [1] to warn when the left hand side is a constant as well now triggers with the modulo expression in nsecs_to_jiffies_timeout() when NSEC_PER_SEC is not a multiple of HZ, such as CONFIG_HZ=300: drivers/gpu/drm/i915/gem/i915_gem_wait.c:189:24: warning: use of logical '&&' with constant operand [-Wconstant-logical-operand] 189 | if (NSEC_PER_SEC % HZ && | ~~~~~~~~~~~~~~~~~ ^ drivers/gpu/drm/i915/gem/i915_gem_wait.c:189:24: note: use '&' for a bitwise operation 189 | if (NSEC_PER_SEC % HZ && | ^~ | & drivers/gpu/drm/i915/gem/i915_gem_wait.c:189:24: note: remove constant to silence this warning 1 warning generated. In file included from drivers/gpu/drm/v3d/v3d_debugfs.c:12: drivers/gpu/drm/v3d/v3d_drv.h:343:24: warning: use of logical '&&' with constant operand [-Wconstant-logical-operand] 343 | if (NSEC_PER_SEC % HZ && | ~~~~~~~~~~~~~~~~~ ^ drivers/gpu/drm/v3d/v3d_drv.h:343:24: note: use '&' for a bitwise operation 343 | if (NSEC_PER_SEC % HZ && | ^~ | & drivers/gpu/drm/v3d/v3d_drv.h:343:24: note: remove constant to silence this warning 1 warning generated. These patches add an explicit comparison to zero to make the expression a boolean, which clears up the warning. The patches have no real dependency on each other but I felt like they made send together since it is the same code. If these could go into mainline sooner rather than later to avoid breaking builds that can hit this with CONFIG_WERROR, that would be nice, but I won't insist since I don't think our own CI has builds that has those conditions, but others might. --- Nathan Chancellor (2): drm/v3d: Avoid -Wconstant-logical-operand in nsecs_to_jiffies_timeout() drm/i915: Avoid -Wconstant-logical-operand in nsecs_to_jiffies_timeout() drivers/gpu/drm/i915/gem/i915_gem_wait.c | 2 +- drivers/gpu/drm/v3d/v3d_drv.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) --- base-commit: fdf0eaf11452d72945af31804e2a1048ee1b574c change-id: 20230718-nsecs_to_jiffies_timeout-constant-logical-operand-4a944690f3e9 Best regards,