The patch titled ata: call flush_dcache_page() around PIO data transfers in libata-aff.c has been added to the -mm tree. Its filename is ata-call-flush_dcache_page-around-pio-data-transfers-in-libata-affc.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: ata: call flush_dcache_page() around PIO data transfers in libata-aff.c From: Catalin Marinas <catalin.marinas@xxxxxxx> Depending on the direction of the transfer, flush_dcache_page() must be called either before (ATA_TFLAG_WRITE) or after (!ATA_TFLAG_WRITE) the data copying to avoid D-cache aliasing with user space or I-D cache coherency issues (when reading data from an ATA device using PIO, the kernel dirties the D-cache but there is no flush_dcache_page() required on Harvard architectures). This patch allows the ARM boards to use a rootfs on CompactFlash with the PATA platform driver. As Anfei Zhou mentioned in a recent patch ("flush dcache before writing into page to avoid alias"), on some architectures there may be a performance benefit in differentiating the flush_dcache_page() calls based on whether the kernel or the user page needs flushing. IMHO, we should differentiate based on the direction (kernel reading or writing from/to such page). In the ARM case with PIPT Harvard caches (newer processors), the kernel reading from a page that may be mapped in user space shouldn't need cache flushing. The kernel writing to such page would require D-cache flushing because of coherency with the I-cache. Currently on ARM, the latter happens in both cases. Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Jeff Garzik <jgarzik@xxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: <stable@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/ata/libata-sff.c | 6 ++++++ 1 file changed, 6 insertions(+) diff -puN drivers/ata/libata-sff.c~ata-call-flush_dcache_page-around-pio-data-transfers-in-libata-affc drivers/ata/libata-sff.c --- a/drivers/ata/libata-sff.c~ata-call-flush_dcache_page-around-pio-data-transfers-in-libata-affc +++ a/drivers/ata/libata-sff.c @@ -874,6 +874,9 @@ static void ata_pio_sector(struct ata_qu DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read"); + if (do_write) + flush_dcache_page(page); + if (PageHighMem(page)) { unsigned long flags; @@ -893,6 +896,9 @@ static void ata_pio_sector(struct ata_qu do_write); } + if (!do_write) + flush_dcache_page(page); + qc->curbytes += qc->sect_size; qc->cursg_ofs += qc->sect_size; _ Patches currently in -mm which might be from catalin.marinas@xxxxxxx are linux-next.patch ata-call-flush_dcache_page-around-pio-data-transfers-in-libata-affc.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html