forked from Minki/linux
locking/atomics, firmware/ivc: Convert ACCESS_ONCE() to READ_ONCE()/WRITE_ONCE()
workqueue: kill off ACCESS_ONCE() 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 currently harmful. However, for some features it is necessary to instrument reads and writes separately, which is not possible with ACCESS_ONCE(). This distinction is critical to correct operation. It's possible to transform the bulk of kernel code using the Coccinelle script below. However, this doesn't handle comments, leaving references to ACCESS_ONCE() instances which have been removed. As a preparatory step, this patch converts the Tegra IVC code and comments to use {READ,WRITE}_ONCE() consistently. ---- 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: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Jonathan Hunter <jonathanh@nvidia.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thierry Reding <thierry.reding@gmail.com> 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/1508792849-3115-3-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -99,11 +99,11 @@ static inline bool tegra_ivc_empty(struct tegra_ivc *ivc,
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{
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/*
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* This function performs multiple checks on the same values with
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* security implications, so create snapshots with ACCESS_ONCE() to
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* security implications, so create snapshots with READ_ONCE() to
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* ensure that these checks use the same values.
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*/
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u32 tx = ACCESS_ONCE(header->tx.count);
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u32 rx = ACCESS_ONCE(header->rx.count);
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u32 tx = READ_ONCE(header->tx.count);
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u32 rx = READ_ONCE(header->rx.count);
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/*
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* Perform an over-full check to prevent denial of service attacks
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@ -124,8 +124,8 @@ static inline bool tegra_ivc_empty(struct tegra_ivc *ivc,
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static inline bool tegra_ivc_full(struct tegra_ivc *ivc,
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struct tegra_ivc_header *header)
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{
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u32 tx = ACCESS_ONCE(header->tx.count);
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u32 rx = ACCESS_ONCE(header->rx.count);
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u32 tx = READ_ONCE(header->tx.count);
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u32 rx = READ_ONCE(header->rx.count);
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/*
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* Invalid cases where the counters indicate that the queue is over
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@ -137,8 +137,8 @@ static inline bool tegra_ivc_full(struct tegra_ivc *ivc,
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static inline u32 tegra_ivc_available(struct tegra_ivc *ivc,
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struct tegra_ivc_header *header)
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{
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u32 tx = ACCESS_ONCE(header->tx.count);
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u32 rx = ACCESS_ONCE(header->rx.count);
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u32 tx = READ_ONCE(header->tx.count);
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u32 rx = READ_ONCE(header->rx.count);
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/*
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* This function isn't expected to be used in scenarios where an
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@ -151,8 +151,8 @@ static inline u32 tegra_ivc_available(struct tegra_ivc *ivc,
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static inline void tegra_ivc_advance_tx(struct tegra_ivc *ivc)
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{
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ACCESS_ONCE(ivc->tx.channel->tx.count) =
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ACCESS_ONCE(ivc->tx.channel->tx.count) + 1;
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WRITE_ONCE(ivc->tx.channel->tx.count,
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READ_ONCE(ivc->tx.channel->tx.count) + 1);
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if (ivc->tx.position == ivc->num_frames - 1)
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ivc->tx.position = 0;
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@ -162,8 +162,8 @@ static inline void tegra_ivc_advance_tx(struct tegra_ivc *ivc)
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static inline void tegra_ivc_advance_rx(struct tegra_ivc *ivc)
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{
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ACCESS_ONCE(ivc->rx.channel->rx.count) =
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ACCESS_ONCE(ivc->rx.channel->rx.count) + 1;
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WRITE_ONCE(ivc->rx.channel->rx.count,
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READ_ONCE(ivc->rx.channel->rx.count) + 1);
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if (ivc->rx.position == ivc->num_frames - 1)
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ivc->rx.position = 0;
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@ -428,7 +428,7 @@ int tegra_ivc_notified(struct tegra_ivc *ivc)
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/* Copy the receiver's state out of shared memory. */
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tegra_ivc_invalidate(ivc, ivc->rx.phys + offset);
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state = ACCESS_ONCE(ivc->rx.channel->tx.state);
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state = READ_ONCE(ivc->rx.channel->tx.state);
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if (state == TEGRA_IVC_STATE_SYNC) {
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offset = offsetof(struct tegra_ivc_header, tx.count);
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