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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/acpi/apei
parent818b667ba57f68bf1e7240fa441dda0b11e6b944 (diff)
downloadop-kernel-dev-dbee8a0affd5e6eaa5d7c816c4bc233f6f110f50.zip
op-kernel-dev-dbee8a0affd5e6eaa5d7c816c4bc233f6f110f50.tar.gz
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/acpi/apei')
-rw-r--r--drivers/acpi/apei/einj.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj.c
index 096aebf..f74b2ea 100644
--- a/drivers/acpi/apei/einj.c
+++ b/drivers/acpi/apei/einj.c
@@ -101,6 +101,14 @@ static DEFINE_MUTEX(einj_mutex);
static struct einj_parameter *einj_param;
+#ifndef writeq
+static inline void writeq(__u64 val, volatile void __iomem *addr)
+{
+ writel(val, addr);
+ writel(val >> 32, addr+4);
+}
+#endif
+
static void einj_exec_ctx_init(struct apei_exec_context *ctx)
{
apei_exec_ctx_init(ctx, einj_ins_type, ARRAY_SIZE(einj_ins_type),
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