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author | Thomas Gleixner <tglx@linutronix.de> | 2016-07-29 17:32:30 +0300 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2016-07-29 19:44:14 +0300 |
commit | 784bdf3bb694b256fcd6120b93e8947a84249a3a (patch) | |
tree | cac56fdf1567db581d4f2a504dac6e75f878978d /include/asm-generic/qrwlock.h | |
parent | e65805251f2db69c9f67ed8062ab82526be5a374 (diff) | |
download | linux-784bdf3bb694b256fcd6120b93e8947a84249a3a.tar.xz |
futex: Assume all mappings are private on !MMU systems
To quote Rick why there is no need for shared mapping on !MMU systems:
|With MMU, shared futex keys need to identify the physical backing for
|a memory address because it may be mapped at different addresses in
|different processes (or even multiple times in the same process).
|Without MMU this cannot happen. You only have physical addresses. So
|the "private futex" behavior of using the virtual address as the key
|is always correct (for both shared and private cases) on nommu
|systems.
This patch disables the FLAGS_SHARED in a way that allows the compiler to
remove that code.
[bigeasy: Added changelog ]
Reported-by: Rich Felker <dalias@libc.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20160729143230.GA21715@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include/asm-generic/qrwlock.h')
0 files changed, 0 insertions, 0 deletions