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authorChristoph Hellwig <hch@lst.de>2021-09-02 14:56:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-09-03 09:58:13 -0700
commit79c62de859f7e854399efb84a2f04ceeb1c13cc9 (patch)
tree5cd41e4dbf7dcbfb012fd4cc4d984f2eb31b56d1 /drivers/mmc
parent0c52ec9513b309b250046fdb2c4c6c3726fa5cfb (diff)
mmc: JZ4740: remove the flush_kernel_dcache_page call in jz4740_mmc_read_data
Patch series "_kernel_dcache_page fixes and removal". While looking to convert the block layer away from kmap_atomic towards kmap_local_page and prefeably the helpers that abstract it away I noticed that a few block drivers directly or implicitly call flush_kernel_dcache_page before kunmapping a page that has been written to. flush_kernel_dcache_page is documented to to be used in such cases, but flush_dcache_page is actually required when the page could be in the page cache and mapped to userspace, which is pretty much always the case when kmapping an arbitrary page. Unfortunately the documentation doesn't exactly make that clear, which lead to this misused. And it turns out that only the copy_strings / copy_string_kernel in the exec code were actually correct users of flush_kernel_dcache_page, which is why I think we should just remove it and eat the very minor overhead in exec rather than confusing poor driver writers. This patch (of 6): MIPS now implements flush_kernel_dcache_page (as an alias to flush_dcache_page). Link: https://lkml.kernel.org/r/20210712060928.4161649-1-hch@lst.de Link: https://lkml.kernel.org/r/20210712060928.4161649-2-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Guo Ren <guoren@kernel.org> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Nick Hu <nickhu@andestech.com> Cc: Greentime Hu <green.hu@gmail.com> Cc: Vincent Chen <deanbo422@gmail.com> Cc: Helge Deller <deller@gmx.de> Cc: Yoshinori Sato <ysato@users.osdn.me> Cc: Rich Felker <dalias@libc.org> Cc: Geoff Levand <geoff@infradead.org> Cc: Paul Cercueil <paul@crapouillou.net> Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: Alex Shi <alexs@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/mmc')
-rw-r--r--drivers/mmc/host/jz4740_mmc.c4
1 files changed, 0 insertions, 4 deletions
diff --git a/drivers/mmc/host/jz4740_mmc.c b/drivers/mmc/host/jz4740_mmc.c
index cb1a64a5c256..80a2c270d502 100644
--- a/drivers/mmc/host/jz4740_mmc.c
+++ b/drivers/mmc/host/jz4740_mmc.c
@@ -578,10 +578,6 @@ static bool jz4740_mmc_read_data(struct jz4740_mmc_host *host,
}
}
data->bytes_xfered += miter->length;
-
- /* This can go away once MIPS implements
- * flush_kernel_dcache_page */
- flush_dcache_page(miter->page);
}
sg_miter_stop(miter);