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* [PATCH] nvme: use upper_32_bits() instead of bit shift
@ 2018-03-28 13:57 ` Arnd Bergmann
  0 siblings, 0 replies; 6+ messages in thread
From: Arnd Bergmann @ 2018-03-28 13:57 UTC (permalink / raw)
  To: Keith Busch, Jens Axboe, Christoph Hellwig, Sagi Grimberg
  Cc: Matias Bjørling, Arnd Bergmann, Johannes Thumshirn,
	Hannes Reinecke, linux-nvme, linux-kernel

On 32-bit architectures, we cannot shift a size_t by 32 bits to the right
without a compiler warning:

drivers/nvme/host/core.c: In function 'nvme_get_log_ext':
drivers/nvme/host/core.c:2237:43: error: right shift count >= width of type [-Werror=shift-count-overflow]
  c.get_log_page.lpou = cpu_to_le32(offset >> 32ULL);
                                           ^~
include/uapi/linux/byteorder/little_endian.h:33:51: note: in definition of macro '__cpu_to_le32'
 #define __cpu_to_le32(x) ((__force __le32)(__u32)(x))
                                                   ^
drivers/nvme/host/core.c:2237:24: note: in expansion of macro 'cpu_to_le32'
  c.get_log_page.lpou = cpu_to_le32(offset >> 32ULL);

The code is correct, but using the upper_32_bits() and lower_32_bits()
macros that were introduced for this operation makes it easier to read
and avoids the warning.

Fixes: 70da6094a646 ("nvme: implement log page low/high offset and dwords")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/nvme/host/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 4e4136bfc37f..0a81704b763f 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2233,8 +2233,8 @@ int nvme_get_log_ext(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 	c.get_log_page.lid = log_page;
 	c.get_log_page.numdl = cpu_to_le16(dwlen & ((1 << 16) - 1));
 	c.get_log_page.numdu = cpu_to_le16(dwlen >> 16);
-	c.get_log_page.lpol = cpu_to_le32(offset & ((1ULL << 32) - 1));
-	c.get_log_page.lpou = cpu_to_le32(offset >> 32ULL);
+	c.get_log_page.lpol = cpu_to_le32(lower_32_bits(offset));
+	c.get_log_page.lpou = cpu_to_le32(upper_32_bits(offset));
 
 	return nvme_submit_sync_cmd(ctrl->admin_q, &c, log, size);
 }
-- 
2.9.0

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [PATCH] nvme: use upper_32_bits() instead of bit shift
@ 2018-03-28 13:57 ` Arnd Bergmann
  0 siblings, 0 replies; 6+ messages in thread
From: Arnd Bergmann @ 2018-03-28 13:57 UTC (permalink / raw)


On 32-bit architectures, we cannot shift a size_t by 32 bits to the right
without a compiler warning:

drivers/nvme/host/core.c: In function 'nvme_get_log_ext':
drivers/nvme/host/core.c:2237:43: error: right shift count >= width of type [-Werror=shift-count-overflow]
  c.get_log_page.lpou = cpu_to_le32(offset >> 32ULL);
                                           ^~
include/uapi/linux/byteorder/little_endian.h:33:51: note: in definition of macro '__cpu_to_le32'
 #define __cpu_to_le32(x) ((__force __le32)(__u32)(x))
                                                   ^
drivers/nvme/host/core.c:2237:24: note: in expansion of macro 'cpu_to_le32'
  c.get_log_page.lpou = cpu_to_le32(offset >> 32ULL);

The code is correct, but using the upper_32_bits() and lower_32_bits()
macros that were introduced for this operation makes it easier to read
and avoids the warning.

Fixes: 70da6094a646 ("nvme: implement log page low/high offset and dwords")
Signed-off-by: Arnd Bergmann <arnd at arndb.de>
---
 drivers/nvme/host/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 4e4136bfc37f..0a81704b763f 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2233,8 +2233,8 @@ int nvme_get_log_ext(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 	c.get_log_page.lid = log_page;
 	c.get_log_page.numdl = cpu_to_le16(dwlen & ((1 << 16) - 1));
 	c.get_log_page.numdu = cpu_to_le16(dwlen >> 16);
-	c.get_log_page.lpol = cpu_to_le32(offset & ((1ULL << 32) - 1));
-	c.get_log_page.lpou = cpu_to_le32(offset >> 32ULL);
+	c.get_log_page.lpol = cpu_to_le32(lower_32_bits(offset));
+	c.get_log_page.lpou = cpu_to_le32(upper_32_bits(offset));
 
 	return nvme_submit_sync_cmd(ctrl->admin_q, &c, log, size);
 }
-- 
2.9.0

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH] nvme: use upper_32_bits() instead of bit shift
  2018-03-28 13:57 ` Arnd Bergmann
@ 2018-03-28 14:05   ` Johannes Thumshirn
  -1 siblings, 0 replies; 6+ messages in thread
From: Johannes Thumshirn @ 2018-03-28 14:05 UTC (permalink / raw)
  To: Arnd Bergmann, Keith Busch, Jens Axboe, Christoph Hellwig, Sagi Grimberg
  Cc: Matias Bjørling, Hannes Reinecke, linux-nvme, linux-kernel

Looks good,
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
-- 
Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH] nvme: use upper_32_bits() instead of bit shift
@ 2018-03-28 14:05   ` Johannes Thumshirn
  0 siblings, 0 replies; 6+ messages in thread
From: Johannes Thumshirn @ 2018-03-28 14:05 UTC (permalink / raw)


Looks good,
Reviewed-by: Johannes Thumshirn <jthumshirn at suse.de>
-- 
Johannes Thumshirn                                          Storage
jthumshirn at suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N?rnberg
GF: Felix Imend?rffer, Jane Smithard, Graham Norton
HRB 21284 (AG N?rnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] nvme: use upper_32_bits() instead of bit shift
  2018-03-28 13:57 ` Arnd Bergmann
@ 2018-03-28 14:20   ` Keith Busch
  -1 siblings, 0 replies; 6+ messages in thread
From: Keith Busch @ 2018-03-28 14:20 UTC (permalink / raw)
  To: Arnd Bergmann
  Cc: Jens Axboe, Christoph Hellwig, Sagi Grimberg,
	Matias Bjørling, Johannes Thumshirn, Hannes Reinecke,
	linux-nvme, linux-kernel

On Wed, Mar 28, 2018 at 03:57:47PM +0200, Arnd Bergmann wrote:
> @@ -2233,8 +2233,8 @@ int nvme_get_log_ext(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
>  	c.get_log_page.lid = log_page;
>  	c.get_log_page.numdl = cpu_to_le16(dwlen & ((1 << 16) - 1));
>  	c.get_log_page.numdu = cpu_to_le16(dwlen >> 16);
> -	c.get_log_page.lpol = cpu_to_le32(offset & ((1ULL << 32) - 1));
> -	c.get_log_page.lpou = cpu_to_le32(offset >> 32ULL);
> +	c.get_log_page.lpol = cpu_to_le32(lower_32_bits(offset));
> +	c.get_log_page.lpou = cpu_to_le32(upper_32_bits(offset));
>  
>  	return nvme_submit_sync_cmd(ctrl->admin_q, &c, log, size);
>  }

Right, Matias posted the same fix here:

 http://lists.infradead.org/pipermail/linux-nvme/2018-March/016474.html

In addition to the type safe shifting, a 64-bit type was used to match
the spec.

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH] nvme: use upper_32_bits() instead of bit shift
@ 2018-03-28 14:20   ` Keith Busch
  0 siblings, 0 replies; 6+ messages in thread
From: Keith Busch @ 2018-03-28 14:20 UTC (permalink / raw)


On Wed, Mar 28, 2018@03:57:47PM +0200, Arnd Bergmann wrote:
> @@ -2233,8 +2233,8 @@ int nvme_get_log_ext(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
>  	c.get_log_page.lid = log_page;
>  	c.get_log_page.numdl = cpu_to_le16(dwlen & ((1 << 16) - 1));
>  	c.get_log_page.numdu = cpu_to_le16(dwlen >> 16);
> -	c.get_log_page.lpol = cpu_to_le32(offset & ((1ULL << 32) - 1));
> -	c.get_log_page.lpou = cpu_to_le32(offset >> 32ULL);
> +	c.get_log_page.lpol = cpu_to_le32(lower_32_bits(offset));
> +	c.get_log_page.lpou = cpu_to_le32(upper_32_bits(offset));
>  
>  	return nvme_submit_sync_cmd(ctrl->admin_q, &c, log, size);
>  }

Right, Matias posted the same fix here:

 http://lists.infradead.org/pipermail/linux-nvme/2018-March/016474.html

In addition to the type safe shifting, a 64-bit type was used to match
the spec.

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2018-03-28 14:20 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-03-28 13:57 [PATCH] nvme: use upper_32_bits() instead of bit shift Arnd Bergmann
2018-03-28 13:57 ` Arnd Bergmann
2018-03-28 14:05 ` Johannes Thumshirn
2018-03-28 14:05   ` Johannes Thumshirn
2018-03-28 14:20 ` Keith Busch
2018-03-28 14:20   ` Keith Busch

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