From 332efa6374de75c622b782569b16bb50fd722cf5 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Mon, 23 Oct 2017 14:07:12 -0700 Subject: [PATCH] locking/atomics, EDAC/altera: Convert ACCESS_ONCE() to READ_ONCE()/WRITE_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 Altera EDAC 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 Signed-off-by: Paul E. McKenney Acked-by: Thor Thayer Cc: Borislav Petkov 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: tj@kernel.org Cc: viro@zeniv.linux.org.uk Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1508792849-3115-2-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar --- drivers/edac/altera_edac.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/edac/altera_edac.c b/drivers/edac/altera_edac.c index 346c4987b284..11d6419788c2 100644 --- a/drivers/edac/altera_edac.c +++ b/drivers/edac/altera_edac.c @@ -175,11 +175,11 @@ static ssize_t altr_sdr_mc_err_inject_write(struct file *file, /* * To trigger the error, we need to read the data back * (the data was written with errors above). - * The ACCESS_ONCE macros and printk are used to prevent the + * The READ_ONCE macros and printk are used to prevent the * the compiler optimizing these reads out. */ - reg = ACCESS_ONCE(ptemp[0]); - read_reg = ACCESS_ONCE(ptemp[1]); + reg = READ_ONCE(ptemp[0]); + read_reg = READ_ONCE(ptemp[1]); /* Force Read */ rmb(); @@ -618,7 +618,7 @@ static ssize_t altr_edac_device_trig(struct file *file, for (i = 0; i < (priv->trig_alloc_sz / sizeof(*ptemp)); i++) { /* Read data so we're in the correct state */ rmb(); - if (ACCESS_ONCE(ptemp[i])) + if (READ_ONCE(ptemp[i])) result = -1; /* Toggle Error bit (it is latched), leave ECC enabled */ writel(error_mask, (drvdata->base + priv->set_err_ofst)); @@ -635,7 +635,7 @@ static ssize_t altr_edac_device_trig(struct file *file, /* Read out written data. ECC error caused here */ for (i = 0; i < ALTR_TRIGGER_READ_WRD_CNT; i++) - if (ACCESS_ONCE(ptemp[i]) != i) + if (READ_ONCE(ptemp[i]) != i) edac_printk(KERN_ERR, EDAC_DEVICE, "Read doesn't match written data\n");