• Mark Rutland's avatar
    locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns... · 6aa7de05
    Mark Rutland authored
    locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()
    
    Please do not apply this to mainline directly, instead please re-run the
    coccinelle script shown below and apply its output.
    
    For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
    preference to ACCESS_ONCE(), and new code is expected to use one of the
    former. So far, there's been no reason to change most existing uses of
    ACCESS_ONCE(), as these aren't harmful, and changing them results in
    churn.
    
    However, for some features, the read/write distinction is critical to
    correct operation. To distinguish these cases, separate read/write
    accessors must be used. This patch migrates (most) remaining
    ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
    coccinelle script:
    
    ----
    // Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
    // WRITE_ONCE()
    
    // $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch
    
    virtual patch
    
    @ depends on patch @
    expression E1, E2;
    @@
    
    - ACCESS_ONCE(E1) = E2
    + WRITE_ONCE(E1, E2)
    
    @ depends on patch @
    expression E;
    @@
    
    - ACCESS_ONCE(E)
    + READ_ONCE(E)
    ----
    Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
    Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: davem@davemloft.net
    Cc: linux-arch@vger.kernel.org
    Cc: mpe@ellerman.id.au
    Cc: shuah@kernel.org
    Cc: snitzer@redhat.com
    Cc: thor.thayer@linux.intel.com
    Cc: tj@kernel.org
    Cc: viro@zeniv.linux.org.uk
    Cc: will.deacon@arm.com
    Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    6aa7de05
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