From 6aa7de059173a986114ac43b8f50b297a86f09a8 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Mon, 23 Oct 2017 14:07:29 -0700 Subject: 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: Mark Rutland Signed-off-by: Paul E. McKenney Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner 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.com Signed-off-by: Ingo Molnar --- drivers/firewire/ohci.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) (limited to 'drivers/firewire') diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c index 8bf89267dc25..ccf52368a073 100644 --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -734,7 +734,7 @@ static unsigned int ar_search_last_active_buffer(struct ar_context *ctx, __le16 res_count, next_res_count; i = ar_first_buffer_index(ctx); - res_count = ACCESS_ONCE(ctx->descriptors[i].res_count); + res_count = READ_ONCE(ctx->descriptors[i].res_count); /* A buffer that is not yet completely filled must be the last one. */ while (i != last && res_count == 0) { @@ -742,8 +742,7 @@ static unsigned int ar_search_last_active_buffer(struct ar_context *ctx, /* Peek at the next descriptor. */ next_i = ar_next_buffer_index(i); rmb(); /* read descriptors in order */ - next_res_count = ACCESS_ONCE( - ctx->descriptors[next_i].res_count); + next_res_count = READ_ONCE(ctx->descriptors[next_i].res_count); /* * If the next descriptor is still empty, we must stop at this * descriptor. @@ -759,8 +758,7 @@ static unsigned int ar_search_last_active_buffer(struct ar_context *ctx, if (MAX_AR_PACKET_SIZE > PAGE_SIZE && i != last) { next_i = ar_next_buffer_index(next_i); rmb(); - next_res_count = ACCESS_ONCE( - ctx->descriptors[next_i].res_count); + next_res_count = READ_ONCE(ctx->descriptors[next_i].res_count); if (next_res_count != cpu_to_le16(PAGE_SIZE)) goto next_buffer_is_active; } @@ -2812,7 +2810,7 @@ static int handle_ir_buffer_fill(struct context *context, u32 buffer_dma; req_count = le16_to_cpu(last->req_count); - res_count = le16_to_cpu(ACCESS_ONCE(last->res_count)); + res_count = le16_to_cpu(READ_ONCE(last->res_count)); completed = req_count - res_count; buffer_dma = le32_to_cpu(last->data_address); -- cgit