On Fri, 2011-05-20 at 13:44 +0200, Ingo Molnar wrote: > * Roland Dreier <roland@xxxxxxxxxx> wrote: > > > From: Roland Dreier <roland@xxxxxxxxxxxxxxx> > > > > 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@xxxxxxxxx>). 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 mean time 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@xxxxxxxxxxx > > Cc: Hitoshi Mitake <h.mitake@xxxxxxxxx> > > Cc: Kashyap Desai <Kashyap.Desai@xxxxxxx> > > Cc: Len Brown <lenb@xxxxxxxxxx> > > Cc: Ravi Anand <ravi.anand@xxxxxxxxxx> > > Cc: Vikas Chaudhary <vikas.chaudhary@xxxxxxxxxx> > > Cc: Matthew Garrett <mjg@xxxxxxxxxx> > > Signed-off-by: Roland Dreier <roland@xxxxxxxxxxxxxxx> > > --- > > arch/x86/Kconfig | 2 -- > > arch/x86/include/asm/io.h | 24 ++---------------------- > > drivers/acpi/apei/einj.c | 8 ++++++++ > > drivers/acpi/atomicio.c | 4 ++++ > > drivers/edac/i3200_edac.c | 13 +++++++++++++ > > drivers/platform/x86/ibm_rtl.c | 13 +++++++++++++ > > drivers/platform/x86/intel_ips.c | 13 +++++++++++++ > > drivers/scsi/qla4xxx/ql4_nx.c | 21 +++++++++++++++++++++ > > 8 files changed, 74 insertions(+), 24 deletions(-) > > Hm, this patch is wider than i thought - might be better to do this via one of > the driver trees or -mm? We don't have a single driver tree covering all of those, so I think the x86 tree is as good as any other > The x86 bits are: > > Acked-by: Ingo Molnar <mingo@xxxxxxx> For the SCSI bits: Acked-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxx> James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
