* [PATCH] mtd: devices: m25p80: Make the buffer passed in op is DMA-able
@ 2018-09-17 13:36 Boris Brezillon
2018-09-17 13:38 ` Boris Brezillon
2018-09-17 14:13 ` Jarkko Nikula
0 siblings, 2 replies; 4+ messages in thread
From: Boris Brezillon @ 2018-09-17 13:36 UTC (permalink / raw)
To: David Woodhouse, Brian Norris, Boris Brezillon, Marek Vasut,
Richard Weinberger, linux-mtd
Cc: Jarkko Nikula, stable
As documented in spi-mem.h, spi_mem_op->data.buf.{in,out} must be
DMA-able, and commit 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx()
API") failed to follow this rule as buffers passed to
->{read,write}_reg() are usually placed on the stack.
Fix that by allocating a scratch buffer and copying the data in there
before passing it to the spi-mem layer.
Fixes: 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API")
Reported-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
---
Note that the ->{read,write}() path is still buggy since nothing
guarantees that buffers passed by the MTD layer to the SPI NOR layer
are DMA-able, but this is a long-standing issue which we'll have to
address at the spi-nor level (this layer can choose the bounce buffer
size based on nor->page_size).
---
drivers/mtd/devices/m25p80.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index cbfafc453274..3b7fafa4bbd6 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -39,14 +39,22 @@ static int m25p80_read_reg(struct spi_nor *nor, u8 code, u8 *val, int len)
struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(code, 1),
SPI_MEM_OP_NO_ADDR,
SPI_MEM_OP_NO_DUMMY,
- SPI_MEM_OP_DATA_IN(len, val, 1));
+ SPI_MEM_OP_DATA_IN(len, NULL, 1));
+ void *scratchbuf;
int ret;
+ scratchbuf = kmemdup(val, len, GFP_KERNEL);
+ if (!scratchbuf)
+ return -ENOMEM;
+
+ op.data.buf.in = scratchbuf;
ret = spi_mem_exec_op(flash->spimem, &op);
if (ret < 0)
dev_err(&flash->spimem->spi->dev, "error %d reading %x\n", ret,
code);
+ kfree(scratchbuf);
+
return ret;
}
@@ -56,9 +64,19 @@ static int m25p80_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(opcode, 1),
SPI_MEM_OP_NO_ADDR,
SPI_MEM_OP_NO_DUMMY,
- SPI_MEM_OP_DATA_OUT(len, buf, 1));
+ SPI_MEM_OP_DATA_OUT(len, NULL, 1));
+ void *scratchbuf;
+ int ret;
- return spi_mem_exec_op(flash->spimem, &op);
+ scratchbuf = kmemdup(buf, len, GFP_KERNEL);
+ if (!scratchbuf)
+ return -ENOMEM;
+
+ op.data.buf.out = scratchbuf;
+ ret = spi_mem_exec_op(flash->spimem, &op);
+ kfree(scratchbuf);
+
+ return ret;
}
static ssize_t m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
--
2.14.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] mtd: devices: m25p80: Make the buffer passed in op is DMA-able
2018-09-17 13:36 [PATCH] mtd: devices: m25p80: Make the buffer passed in op is DMA-able Boris Brezillon
@ 2018-09-17 13:38 ` Boris Brezillon
2018-09-17 14:13 ` Jarkko Nikula
1 sibling, 0 replies; 4+ messages in thread
From: Boris Brezillon @ 2018-09-17 13:38 UTC (permalink / raw)
To: David Woodhouse, Brian Norris, Boris Brezillon, Marek Vasut,
Richard Weinberger, linux-mtd
Cc: Jarkko Nikula, stable
Oops. You should read "Make *sure* ...".
On Mon, 17 Sep 2018 15:36:52 +0200
Boris Brezillon <boris.brezillon@bootlin.com> wrote:
> As documented in spi-mem.h, spi_mem_op->data.buf.{in,out} must be
> DMA-able, and commit 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx()
> API") failed to follow this rule as buffers passed to
> ->{read,write}_reg() are usually placed on the stack.
>
> Fix that by allocating a scratch buffer and copying the data in there
> before passing it to the spi-mem layer.
>
> Fixes: 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API")
> Reported-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> ---
> Note that the ->{read,write}() path is still buggy since nothing
> guarantees that buffers passed by the MTD layer to the SPI NOR layer
> are DMA-able, but this is a long-standing issue which we'll have to
> address at the spi-nor level (this layer can choose the bounce buffer
> size based on nor->page_size).
> ---
> drivers/mtd/devices/m25p80.c | 24 +++++++++++++++++++++---
> 1 file changed, 21 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
> index cbfafc453274..3b7fafa4bbd6 100644
> --- a/drivers/mtd/devices/m25p80.c
> +++ b/drivers/mtd/devices/m25p80.c
> @@ -39,14 +39,22 @@ static int m25p80_read_reg(struct spi_nor *nor, u8 code, u8 *val, int len)
> struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(code, 1),
> SPI_MEM_OP_NO_ADDR,
> SPI_MEM_OP_NO_DUMMY,
> - SPI_MEM_OP_DATA_IN(len, val, 1));
> + SPI_MEM_OP_DATA_IN(len, NULL, 1));
> + void *scratchbuf;
> int ret;
>
> + scratchbuf = kmemdup(val, len, GFP_KERNEL);
> + if (!scratchbuf)
> + return -ENOMEM;
> +
> + op.data.buf.in = scratchbuf;
> ret = spi_mem_exec_op(flash->spimem, &op);
> if (ret < 0)
> dev_err(&flash->spimem->spi->dev, "error %d reading %x\n", ret,
> code);
>
> + kfree(scratchbuf);
> +
> return ret;
> }
>
> @@ -56,9 +64,19 @@ static int m25p80_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
> struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(opcode, 1),
> SPI_MEM_OP_NO_ADDR,
> SPI_MEM_OP_NO_DUMMY,
> - SPI_MEM_OP_DATA_OUT(len, buf, 1));
> + SPI_MEM_OP_DATA_OUT(len, NULL, 1));
> + void *scratchbuf;
> + int ret;
>
> - return spi_mem_exec_op(flash->spimem, &op);
> + scratchbuf = kmemdup(buf, len, GFP_KERNEL);
> + if (!scratchbuf)
> + return -ENOMEM;
> +
> + op.data.buf.out = scratchbuf;
> + ret = spi_mem_exec_op(flash->spimem, &op);
> + kfree(scratchbuf);
> +
> + return ret;
> }
>
> static ssize_t m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] mtd: devices: m25p80: Make the buffer passed in op is DMA-able
2018-09-17 13:36 [PATCH] mtd: devices: m25p80: Make the buffer passed in op is DMA-able Boris Brezillon
2018-09-17 13:38 ` Boris Brezillon
@ 2018-09-17 14:13 ` Jarkko Nikula
2018-09-17 14:22 ` Boris Brezillon
1 sibling, 1 reply; 4+ messages in thread
From: Jarkko Nikula @ 2018-09-17 14:13 UTC (permalink / raw)
To: Boris Brezillon, David Woodhouse, Brian Norris, Marek Vasut,
Richard Weinberger, linux-mtd
Cc: stable
On 09/17/2018 04:36 PM, Boris Brezillon wrote:
> As documented in spi-mem.h, spi_mem_op->data.buf.{in,out} must be
> DMA-able, and commit 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx()
> API") failed to follow this rule as buffers passed to
> ->{read,write}_reg() are usually placed on the stack.
>
> Fix that by allocating a scratch buffer and copying the data in there
> before passing it to the spi-mem layer.
>
> Fixes: 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API")
> Reported-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> ---
> Note that the ->{read,write}() path is still buggy since nothing
> guarantees that buffers passed by the MTD layer to the SPI NOR layer
> are DMA-able, but this is a long-standing issue which we'll have to
> address at the spi-nor level (this layer can choose the bounce buffer
> size based on nor->page_size).
> ---
> drivers/mtd/devices/m25p80.c | 24 +++++++++++++++++++++---
> 1 file changed, 21 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
> index cbfafc453274..3b7fafa4bbd6 100644
> --- a/drivers/mtd/devices/m25p80.c
> +++ b/drivers/mtd/devices/m25p80.c
> @@ -39,14 +39,22 @@ static int m25p80_read_reg(struct spi_nor *nor, u8 code, u8 *val, int len)
> struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(code, 1),
> SPI_MEM_OP_NO_ADDR,
> SPI_MEM_OP_NO_DUMMY,
> - SPI_MEM_OP_DATA_IN(len, val, 1));
> + SPI_MEM_OP_DATA_IN(len, NULL, 1));
> + void *scratchbuf;
> int ret;
>
> + scratchbuf = kmemdup(val, len, GFP_KERNEL);
> + if (!scratchbuf)
> + return -ENOMEM;
> +
> + op.data.buf.in = scratchbuf;
> ret = spi_mem_exec_op(flash->spimem, &op);
> if (ret < 0)
> dev_err(&flash->spimem->spi->dev, "error %d reading %x\n", ret,
> code);
>
> + kfree(scratchbuf);
> +
Actually this makes things even worse: "unrecognized JEDEC id bytes: b1,
74, 01" since we don't copy scratchbuf to original buffer and kmemdup
before bus read is needless :-)
--
Jarkko
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] mtd: devices: m25p80: Make the buffer passed in op is DMA-able
2018-09-17 14:13 ` Jarkko Nikula
@ 2018-09-17 14:22 ` Boris Brezillon
0 siblings, 0 replies; 4+ messages in thread
From: Boris Brezillon @ 2018-09-17 14:22 UTC (permalink / raw)
To: Jarkko Nikula
Cc: David Woodhouse, Brian Norris, Marek Vasut, Richard Weinberger,
linux-mtd, stable
On Mon, 17 Sep 2018 17:13:32 +0300
Jarkko Nikula <jarkko.nikula@linux.intel.com> wrote:
> On 09/17/2018 04:36 PM, Boris Brezillon wrote:
> > As documented in spi-mem.h, spi_mem_op->data.buf.{in,out} must be
> > DMA-able, and commit 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx()
> > API") failed to follow this rule as buffers passed to
> > ->{read,write}_reg() are usually placed on the stack.
> >
> > Fix that by allocating a scratch buffer and copying the data in there
> > before passing it to the spi-mem layer.
> >
> > Fixes: 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API")
> > Reported-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
> > Cc: <stable@vger.kernel.org>
> > Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> > ---
> > Note that the ->{read,write}() path is still buggy since nothing
> > guarantees that buffers passed by the MTD layer to the SPI NOR layer
> > are DMA-able, but this is a long-standing issue which we'll have to
> > address at the spi-nor level (this layer can choose the bounce buffer
> > size based on nor->page_size).
> > ---
> > drivers/mtd/devices/m25p80.c | 24 +++++++++++++++++++++---
> > 1 file changed, 21 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
> > index cbfafc453274..3b7fafa4bbd6 100644
> > --- a/drivers/mtd/devices/m25p80.c
> > +++ b/drivers/mtd/devices/m25p80.c
> > @@ -39,14 +39,22 @@ static int m25p80_read_reg(struct spi_nor *nor, u8 code, u8 *val, int len)
> > struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(code, 1),
> > SPI_MEM_OP_NO_ADDR,
> > SPI_MEM_OP_NO_DUMMY,
> > - SPI_MEM_OP_DATA_IN(len, val, 1));
> > + SPI_MEM_OP_DATA_IN(len, NULL, 1));
> > + void *scratchbuf;
> > int ret;
> >
> > + scratchbuf = kmemdup(val, len, GFP_KERNEL);
> > + if (!scratchbuf)
> > + return -ENOMEM;
> > +
> > + op.data.buf.in = scratchbuf;
> > ret = spi_mem_exec_op(flash->spimem, &op);
> > if (ret < 0)
> > dev_err(&flash->spimem->spi->dev, "error %d reading %x\n", ret,
> > code);
> >
> > + kfree(scratchbuf);
> > +
>
> Actually this makes things even worse: "unrecognized JEDEC id bytes: b1,
> 74, 01" since we don't copy scratchbuf to original buffer and kmemdup
> before bus read is needless :-)
True :-).
I'll fix that and send a v2.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-09-17 14:22 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2018-09-17 13:36 [PATCH] mtd: devices: m25p80: Make the buffer passed in op is DMA-able Boris Brezillon
2018-09-17 13:38 ` Boris Brezillon
2018-09-17 14:13 ` Jarkko Nikula
2018-09-17 14:22 ` Boris Brezillon
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).