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authorRoland Dreier <roland@purestorage.com>2011-05-24 17:13:09 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-05-25 08:39:44 -0700
commitdbee8a0affd5e6eaa5d7c816c4bc233f6f110f50 (patch)
tree485bba5ec4436e9e8c84aacf25590ca8f8a6332b /drivers/edac
parent818b667ba57f68bf1e7240fa441dda0b11e6b944 (diff)
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x86: remove 32-bit versions of readq()/writeq()
The presense of a writeq() implementation on 32-bit x86 that splits the 64-bit write into two 32-bit writes turns out to break the mpt2sas driver (and in general is risky for drivers as was discussed in <http://lkml.kernel.org/r/adaab6c1h7c.fsf@cisco.com>). To fix this, revert 2c5643b1c5c7 ("x86: provide readq()/writeq() on 32-bit too") and follow-on cleanups. This unfortunately leads to pushing non-atomic definitions of readq() and write() to various x86-only drivers that in the meantime started using the definitions in the x86 version of <asm/io.h>. However as discussed exhaustively, this is actually the right thing to do, because the right way to split a 64-bit transaction is hardware dependent and therefore belongs in the hardware driver (eg mpt2sas needs a spinlock to make sure no other accesses occur in between the two halves of the access). Build tested on 32- and 64-bit x86 allmodconfig. Link: http://lkml.kernel.org/r/x86-32-writeq-is-broken@mdm.bga.com Acked-by: Hitoshi Mitake <h.mitake@gmail.com> Cc: Kashyap Desai <Kashyap.Desai@lsi.com> Cc: Len Brown <lenb@kernel.org> Cc: Ravi Anand <ravi.anand@qlogic.com> Cc: Vikas Chaudhary <vikas.chaudhary@qlogic.com> Cc: Matthew Garrett <mjg@redhat.com> Cc: Jason Uhlenkott <juhlenko@akamai.com> Acked-by: James Bottomley <James.Bottomley@parallels.com> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Roland Dreier <roland@purestorage.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/edac')
-rw-r--r--drivers/edac/i3200_edac.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/drivers/edac/i3200_edac.c b/drivers/edac/i3200_edac.c
index d41f9002da45..aa08497a075a 100644
--- a/drivers/edac/i3200_edac.c
+++ b/drivers/edac/i3200_edac.c
@@ -101,6 +101,19 @@ struct i3200_priv {
static int nr_channels;
+#ifndef readq
+static inline __u64 readq(const volatile void __iomem *addr)
+{
+ const volatile u32 __iomem *p = addr;
+ u32 low, high;
+
+ low = readl(p);
+ high = readl(p + 1);
+
+ return low + ((u64)high << 32);
+}
+#endif
+
static int how_many_channels(struct pci_dev *pdev)
{
unsigned char capid0_8b; /* 8th byte of CAPID0 */