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/infiniband/hw/hfi1/sdma.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/infiniband/hw/hfi1/sdma.c') diff --git a/drivers/infiniband/hw/hfi1/sdma.c b/drivers/infiniband/hw/hfi1/sdma.c index 6781bcdb10b3..08346d25441c 100644 --- a/drivers/infiniband/hw/hfi1/sdma.c +++ b/drivers/infiniband/hw/hfi1/sdma.c @@ -1725,7 +1725,7 @@ retry: swhead = sde->descq_head & sde->sdma_mask; /* this code is really bad for cache line trading */ - swtail = ACCESS_ONCE(sde->descq_tail) & sde->sdma_mask; + swtail = READ_ONCE(sde->descq_tail) & sde->sdma_mask; cnt = sde->descq_cnt; if (swhead < swtail) @@ -1872,7 +1872,7 @@ retry: if ((status & sde->idle_mask) && !idle_check_done) { u16 swtail; - swtail = ACCESS_ONCE(sde->descq_tail) & sde->sdma_mask; + swtail = READ_ONCE(sde->descq_tail) & sde->sdma_mask; if (swtail != hwhead) { hwhead = (u16)read_sde_csr(sde, SD(HEAD)); idle_check_done = 1; @@ -2222,7 +2222,7 @@ void sdma_seqfile_dump_sde(struct seq_file *s, struct sdma_engine *sde) u16 len; head = sde->descq_head & sde->sdma_mask; - tail = ACCESS_ONCE(sde->descq_tail) & sde->sdma_mask; + tail = READ_ONCE(sde->descq_tail) & sde->sdma_mask; seq_printf(s, SDE_FMT, sde->this_idx, sde->cpu, sdma_state_name(sde->state.current_state), @@ -3305,7 +3305,7 @@ int sdma_ahg_alloc(struct sdma_engine *sde) return -EINVAL; } while (1) { - nr = ffz(ACCESS_ONCE(sde->ahg_bits)); + nr = ffz(READ_ONCE(sde->ahg_bits)); if (nr > 31) { trace_hfi1_ahg_allocate(sde, -ENOSPC); return -ENOSPC; -- cgit