jump_label: Fix small typos in the documentation
Was reading through the documentation of this code and noticed a few typos, missing commas, etc. Cc: Jason Baron <jbaron@akamai.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Mel Gorman <mgorman@suse.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -8,28 +8,28 @@
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* Copyright (C) 2011-2012 Peter Zijlstra <pzijlstr@redhat.com>
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*
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* Jump labels provide an interface to generate dynamic branches using
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* self-modifying code. Assuming toolchain and architecture support the result
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* of a "if (static_key_false(&key))" statement is a unconditional branch (which
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* self-modifying code. Assuming toolchain and architecture support, the result
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* of a "if (static_key_false(&key))" statement is an unconditional branch (which
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* defaults to false - and the true block is placed out of line).
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*
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* However at runtime we can change the branch target using
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* static_key_slow_{inc,dec}(). These function as a 'reference' count on the key
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* object and for as long as there are references all branches referring to
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* object, and for as long as there are references all branches referring to
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* that particular key will point to the (out of line) true block.
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*
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* Since this relies on modifying code the static_key_slow_{inc,dec}() functions
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* Since this relies on modifying code, the static_key_slow_{inc,dec}() functions
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* must be considered absolute slow paths (machine wide synchronization etc.).
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* OTOH, since the affected branches are unconditional their runtime overhead
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* OTOH, since the affected branches are unconditional, their runtime overhead
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* will be absolutely minimal, esp. in the default (off) case where the total
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* effect is a single NOP of appropriate size. The on case will patch in a jump
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* to the out-of-line block.
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*
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* When the control is directly exposed to userspace it is prudent to delay the
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* When the control is directly exposed to userspace, it is prudent to delay the
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* decrement to avoid high frequency code modifications which can (and do)
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* cause significant performance degradation. Struct static_key_deferred and
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* static_key_slow_dec_deferred() provide for this.
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*
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* Lacking toolchain and or architecture support, it falls back to a simple
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* Lacking toolchain and or architecture support, jump labels fall back to a simple
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* conditional branch.
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*
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* struct static_key my_key = STATIC_KEY_INIT_TRUE;
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@ -43,8 +43,7 @@
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*
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* Not initializing the key (static data is initialized to 0s anyway) is the
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* same as using STATIC_KEY_INIT_FALSE.
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*
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*/
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*/
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#include <linux/types.h>
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#include <linux/compiler.h>
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