Re: [PATCH] xen-blkback: define pr_fmt macro to avoid the duplication of DRV_PFX

From: Chentao (Boby)
Date: Wed Apr 01 2015 - 02:40:45 EST

Thanks roger and joe.

I will adopt your suggestions in my v2 patch.

On 2015/3/31 22:57, Roger Pau Monné wrote:
El 31/03/15 a les 23.14, Tao Chen ha escrit:
Define pr_fmt macro with {xen-blkback: } prefix, then remove all use
of DRV_PFX in the pr and DPRINTK sentences. It will simplify the code.

And if the pr sentences miss a \n, add it in the end. If the DPRINTK
sentences have redundant \n, remove it. It will format the code.

These all make the readability of the code become better.

Thanks for the patch.

Signed-off-by: Tao Chen <boby.chen@xxxxxxxxxx>
drivers/block/xen-blkback/blkback.c | 62 ++++++++++++++++++-------------------
drivers/block/xen-blkback/common.h | 6 ----
drivers/block/xen-blkback/xenbus.c | 18 ++++++-----
3 files changed, 42 insertions(+), 44 deletions(-)

diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index 375d288..f620b5d 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -44,12 +44,6 @@
#include <xen/interface/io/blkif.h>
#include <xen/interface/io/protocols.h>

-#define DRV_PFX "xen-blkback:"
-#define DPRINTK(fmt, args...) \
- pr_debug(DRV_PFX "(%s:%d) " fmt ".\n", \
- __func__, __LINE__, ##args)
* This is the maximum number of segments that would be allowed in indirect
* requests. This value will also be passed to the frontend.
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index b33083e..0dbbfeb 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -14,6 +14,11 @@


+#define pr_fmt(fmt) "xen-blkback: " fmt
+#define DPRINTK(fmt, args...) \
+ pr_debug("(%s:%d) " fmt ".\n", \
+ __func__, __LINE__, ##args)
#include <stdarg.h>
#include <linux/module.h>
#include <linux/kthread.h>
@@ -426,14 +431,14 @@ static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,

if (IS_ERR(bdev)) {
- DPRINTK("xen_vbd_create: device %08x could not be opened.\n",
+ DPRINTK("xen_vbd_create: device %08x could not be opened",
return -ENOENT;

vbd->bdev = bdev;
if (vbd->bdev->bd_disk == NULL) {
- DPRINTK("xen_vbd_create: device %08x doesn't exist.\n",
+ DPRINTK("xen_vbd_create: device %08x doesn't exist",

IMHO this two above should be made a pr_warn probably...

return -ENOENT;
@@ -452,7 +457,7 @@ static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
if (q && blk_queue_secdiscard(q))
vbd->discard_secure = true;

- DPRINTK("Successful creation of handle=%04x (dom=%u)\n",
+ DPRINTK("Successful creation of handle=%04x (dom=%u)",
handle, blkif->domid);

...and this should be turned into a plain pr_debug. And with that we can
get rid of DPRINTK.



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