Re: [PATCH v2] bsg: use pr_debug instead of hand craftet macros

[Joe Perches]

On Tue, 2018-01-23 at 11:55 +0100, Johannes Thumshirn wrote:
> Use pr_debug instead of hand craftet macros. This way it is not needed to
> re-compile the kernel to enable bsg debug outputs and it's possible to
> selectively enable specific prints.

Perhaps the email subject could be improved to describe
the new macro and as well, this macro, without a pr_fmt
define somewhat above it loses the __func__ output too.

Perhaps add a description of the capability of the
dynamic debug facility to add the function name using +f.

> Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
> Cc: Joe Perches <joe@xxxxxxxxxxx>
> Cc: Bart Van Assche <Bart.VanAssche@xxxxxxx>
> 
> ---
> Changes to v1:
> * Aligned arguments (Bart)
> * Include bd->name in macro (Joe)
> ---
>  block/bsg.c | 40 +++++++++++++++++-----------------------
>  1 file changed, 17 insertions(+), 23 deletions(-)
> 
> diff --git a/block/bsg.c b/block/bsg.c
> index 452f94f1c5d4..a1bcbb6ba50b 100644
> --- a/block/bsg.c
> +++ b/block/bsg.c
> @@ -32,6 +32,9 @@
>  #define BSG_DESCRIPTION	"Block layer SCSI generic (bsg) driver"
>  #define BSG_VERSION	"0.4"
>  
> +#define bsg_dbg(bd, fmt, ...) \
> +	pr_debug("%s: " fmt, (bd)->name, ##__VA_ARGS__)
> +
>  struct bsg_device {
>  	struct request_queue *queue;
>  	spinlock_t lock;
> @@ -55,14 +58,6 @@ enum {
>  #define BSG_DEFAULT_CMDS	64
>  #define BSG_MAX_DEVS		32768
>  
> -#undef BSG_DEBUG
> -
> -#ifdef BSG_DEBUG
> -#define dprintk(fmt, args...) printk(KERN_ERR "%s: " fmt, __func__, ##args)
> -#else
> -#define dprintk(fmt, args...)
> -#endif
> -
>  static DEFINE_MUTEX(bsg_mutex);
>  static DEFINE_IDR(bsg_minor_idr);
>  
> @@ -123,7 +118,7 @@ static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)
>  
>  	bc->bd = bd;
>  	INIT_LIST_HEAD(&bc->list);
> -	dprintk("%s: returning free cmd %p\n", bd->name, bc);
> +	bsg_dbg(bd, "returning free cmd %p\n", bc);
>  	return bc;
>  out:
>  	spin_unlock_irq(&bd->lock);
> @@ -222,7 +217,8 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t mode)
>  	if (!bcd->class_dev)
>  		return ERR_PTR(-ENXIO);
>  
> -	dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
> +	bsg_dbg(bd, "map hdr %llx/%u %llx/%u\n",
> +		(unsigned long long) hdr->dout_xferp,
>  		hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
>  		hdr->din_xfer_len);
>  
> @@ -299,8 +295,8 @@ static void bsg_rq_end_io(struct request *rq, blk_status_t status)
>  	struct bsg_device *bd = bc->bd;
>  	unsigned long flags;
>  
> -	dprintk("%s: finished rq %p bc %p, bio %p\n",
> -		bd->name, rq, bc, bc->bio);
> +	bsg_dbg(bd, "finished rq %p bc %p, bio %p\n",
> +		rq, bc, bc->bio);
>  
>  	bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
>  
> @@ -333,7 +329,7 @@ static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
>  	list_add_tail(&bc->list, &bd->busy_list);
>  	spin_unlock_irq(&bd->lock);
>  
> -	dprintk("%s: queueing rq %p, bc %p\n", bd->name, rq, bc);
> +	bsg_dbg(bd, "queueing rq %p, bc %p\n", rq, bc);
>  
>  	rq->end_io_data = bc;
>  	blk_execute_rq_nowait(q, NULL, rq, at_head, bsg_rq_end_io);
> @@ -379,7 +375,7 @@ static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
>  		}
>  	} while (1);
>  
> -	dprintk("%s: returning done %p\n", bd->name, bc);
> +	bsg_dbg(bd, "returning done %p\n", bc);
>  
>  	return bc;
>  }
> @@ -390,7 +386,7 @@ static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
>  	struct scsi_request *req = scsi_req(rq);
>  	int ret = 0;
>  
> -	dprintk("rq %p bio %p 0x%x\n", rq, bio, req->result);
> +	pr_debug("rq %p bio %p 0x%x\n", rq, bio, req->result);
>  	/*
>  	 * fill in all the output members
>  	 */
> @@ -469,7 +465,7 @@ static int bsg_complete_all_commands(struct bsg_device *bd)
>  	struct bsg_command *bc;
>  	int ret, tret;
>  
> -	dprintk("%s: entered\n", bd->name);
> +	bsg_dbg(bd, "entered\n");
>  
>  	/*
>  	 * wait for all commands to complete
> @@ -572,7 +568,7 @@ bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
>  	int ret;
>  	ssize_t bytes_read;
>  
> -	dprintk("%s: read %zd bytes\n", bd->name, count);
> +	bsg_dbg(bd, "read %zd bytes\n", count);
>  
>  	bsg_set_block(bd, file);
>  
> @@ -646,7 +642,7 @@ bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
>  	ssize_t bytes_written;
>  	int ret;
>  
> -	dprintk("%s: write %zd bytes\n", bd->name, count);
> +	bsg_dbg(bd, "write %zd bytes\n", count);
>  
>  	if (unlikely(uaccess_kernel()))
>  		return -EINVAL;
> @@ -664,7 +660,7 @@ bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
>  	if (!bytes_written || err_block_err(ret))
>  		bytes_written = ret;
>  
> -	dprintk("%s: returning %zd\n", bd->name, bytes_written);
> +	bsg_dbg(bd, "returning %zd\n", bytes_written);
>  	return bytes_written;
>  }
>  
> @@ -717,7 +713,7 @@ static int bsg_put_device(struct bsg_device *bd)
>  	hlist_del(&bd->dev_list);
>  	mutex_unlock(&bsg_mutex);
>  
> -	dprintk("%s: tearing down\n", bd->name);
> +	bsg_dbg(bd, "tearing down\n");
>  
>  	/*
>  	 * close can always block
> @@ -744,9 +740,7 @@ static struct bsg_device *bsg_add_device(struct inode *inode,
>  					 struct file *file)
>  {
>  	struct bsg_device *bd;
> -#ifdef BSG_DEBUG
>  	unsigned char buf[32];
> -#endif
>  
>  	if (!blk_queue_scsi_passthrough(rq)) {
>  		WARN_ONCE(true, "Attempt to register a non-SCSI queue\n");
> @@ -771,7 +765,7 @@ static struct bsg_device *bsg_add_device(struct inode *inode,
>  	hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
>  
>  	strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
> -	dprintk("bound to <%s>, max queue %d\n",
> +	bsg_dbg(bd, "bound to <%s>, max queue %d\n",
>  		format_dev_t(buf, inode->i_rdev), bd->max_queue);
>  
>  	mutex_unlock(&bsg_mutex);