| From | Jiri Slaby <> | Subject | [PATCH 3.12 127/176] um: Skip futex_atomic_cmpxchg_inatomic() test | Date | Wed, 28 Jan 2015 15:29:17 +0100 |
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From: Richard Weinberger <richard@nod.at>
3.12-stable review patch. If anyone has any objections, please let me know.
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commit f911d731054ab3d82ee72a16b889e17ca3a2332a upstream.
futex_atomic_cmpxchg_inatomic() does not work on UML because it triggers a copy_from_user() in kernel context. On UML copy_from_user() can only be used if the kernel was called by a real user space process such that UML can use ptrace() to fetch the value.
Reported-by: Miklos Szeredi <miklos@szeredi.hu> Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Richard Weinberger <richard@nod.at> Tested-by: Daniel Walter <d.walter@0x90.at> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- arch/um/Kconfig.common | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/um/Kconfig.common b/arch/um/Kconfig.common index 8ddea1f8006a..0228a6ab9b18 100644 --- a/arch/um/Kconfig.common +++ b/arch/um/Kconfig.common @@ -7,6 +7,7 @@ config UML bool default y select HAVE_UID16 + select HAVE_FUTEX_CMPXCHG if FUTEX select GENERIC_IRQ_SHOW select GENERIC_CPU_DEVICES select GENERIC_IO -- 2.2.2
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