Messages in this thread | | | Date | Thu, 16 Apr 2015 17:39:36 +0200 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH] lockdep: make print_lock_name() robust against non-existing lock_class |
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* Peter Zijlstra | 2015-04-16 17:35:03 [+0200]:
>On Thu, Apr 16, 2015 at 04:50:21PM +0200, Sebastian Andrzej Siewior wrote: > >> Andreas confirmed that it works for him on v3.18 with minor adjustment. >> >> <--- >> + struct held_lock lock = READ_ONCE(*hlock); >> + unsigned int class_idx = lock.class_idx; >> ---> >> > >I'm confused by the need for that. What was the failure with the >proposed patch?
It was tested on v3.18, there might have been a change between v3.18 & 4.0. The patch as-is did no compile:
in file included from arch/x86/include/asm/current.h:4:0, from include/linux/mutex.h:13, from kernel/locking/lockdep.c:29: kernel/locking/lockdep.c: In function ‘print_lock’: kernel/locking/lockdep.c:558:37: error: ‘typeof’ applied to a bit-field unsigned int class_idx = READ_ONCE(hlock->class_idx); ^ include/linux/compiler.h:262:20: note: in definition of macro ‘READ_ONCE’ ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), __u.__c, sizeof(x)); __u.__val; }) ^ include/linux/compiler.h:262:11: error: cannot take address of bit-field ‘class_idx’ ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), __u.__c, sizeof(x)); __u.__val; }) ^ kernel/locking/lockdep.c:558:27: note: in expansion of macro ‘READ_ONCE’ unsigned int class_idx = READ_ONCE(hlock->class_idx); ^ include/linux/compiler.h:262:88: error: ‘sizeof’ applied to a bit-field ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), __u.__c, sizeof(x)); __u.__val; }) ^ kernel/locking/lockdep.c:558:27: note: in expansion of macro ‘READ_ONCE’ unsigned int class_idx = READ_ONCE(hlock->class_idx); ^ scripts/Makefile.build:258: recipe for target 'kernel/locking/lockdep.o' failed
Sebastian
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