mutex_init() invokes __mutex_init() providing the name of the lock and
a pointer to a the lock class. With LOCKDEP enabled this information is
useful but without LOCKDEP it not used at all. Passing the pointer
information of the lock class might be considered negligible but the
name of the lock is passed as well and the string is stored. This
information is wasting storage.
Split __mutex_init() into a _genereic() variant doing the initialisation
of the lock and a _lockdep() version which does _genereic() plus the
lockdep bits. Restrict the lockdep version to lockdep enabled builds
allowing the compiler to remove the unused parameter.
This results in the following size reduction:
text data bss dec filename
| 30237599 8161430 1176624 39575653 vmlinux.defconfig
| 30233269 8149142 1176560 39558971 vmlinux.defconfig.patched
-4.2KiB -12KiB
| 32455099 8471098 12934684 53860881 vmlinux.defconfig.lockdep
| 32455100 8471098 12934684 53860882 vmlinux.defconfig.patched.lockdep
| 27152407 7191822 2068040 36412269 vmlinux.defconfig.preempt_rt
| 27145937 7183630 2067976 36397543 vmlinux.defconfig.patched.preempt_rt
-6.3KiB -8KiB
| 29382020 7505742 13784608 50672370 vmlinux.defconfig.preempt_rt.lockdep
| 29376229 7505742 13784544 50666515 vmlinux.defconfig.patched.preempt_rt.lockdep
-5.6KiB
[peterz: folded fix from boqun]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Link: https://lkml.kernel.org/r/20251125145425.68319-1-boqun.feng@gmail.com
Link: https://patch.msgid.link/20251105142350.Tfeevs2N@linutronix.de
51d7a05452