[PATCH 10/10] scsi: arcmsr: Remove snprintf() from sysfs call-backs and replace with sysfs_emit()

Lee Jones
2024-02-08T08:45:38Z

Since snprintf() has the documented, but still rather strange trait of
returning the length of the data that *would have been* written to the
array if space were available, rather than the arguably more useful
length of data *actually* written, it is usually considered wise to use
something else instead in order to avoid confusion.

In the case of sysfs call-backs, new wrappers exist that do just that.

Link: https://lwn.net/Articles/69419/
Link: https://github.com/KSPP/linux/issues/105
Signed-off-by: Lee Jones <lee@kernel.org>
---
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: support@areca.com.tw
Cc: linux-scsi@vger.kernel.org
---
drivers/scsi/arcmsr/arcmsr_attr.c | 40 ++++++++-----------------------
1 file changed, 10 insertions(+), 30 deletions(-)

diff --git a/drivers/scsi/arcmsr/arcmsr_attr.c b/drivers/scsi/arcmsr/arcmsr_attr.c
index baeb5e7956902..c430c835503be 100644
--- a/drivers/scsi/arcmsr/arcmsr_attr.c
+++ b/drivers/scsi/arcmsr/arcmsr_attr.c
@@ -258,9 +258,7 @@ static ssize_t
arcmsr_attr_host_driver_version(struct device *dev,
struct device_attribute *attr, char *buf)
{
- return snprintf(buf, PAGE_SIZE,
- "%s\n",
- ARCMSR_DRIVER_VERSION);
+ return sysfs_emit(buf, "%s\n", ARCMSR_DRIVER_VERSION);
}

static ssize_t
@@ -270,9 +268,7 @@ arcmsr_attr_host_driver_posted_cmd(struct device *dev,
struct Scsi_Host *host = class_to_shost(dev);
struct AdapterControlBlock *acb =
(struct AdapterControlBlock *) host->hostdata;
- return snprintf(buf, PAGE_SIZE,
- "%4d\n",
- atomic_read(&acb->ccboutstandingcount));
+ return sysfs_emit(buf, "%4d\n", atomic_read(&acb->ccboutstandingcount));
}

static ssize_t
@@ -282,9 +278,7 @@ arcmsr_attr_host_driver_reset(struct device *dev,
struct Scsi_Host *host = class_to_shost(dev);
struct AdapterControlBlock *acb =
(struct AdapterControlBlock *) host->hostdata;
- return snprintf(buf, PAGE_SIZE,
- "%4d\n",
- acb->num_resets);
+ return sysfs_emit(buf, "%4d\n", acb->num_resets);
}

static ssize_t
@@ -294,9 +288,7 @@ arcmsr_attr_host_driver_abort(struct device *dev,
struct Scsi_Host *host = class_to_shost(dev);
struct AdapterControlBlock *acb =
(struct AdapterControlBlock *) host->hostdata;
- return snprintf(buf, PAGE_SIZE,
- "%4d\n",
- acb->num_aborts);
+ return sysfs_emit(buf, "%4d\n", acb->num_aborts);
}

static ssize_t
@@ -306,9 +298,7 @@ arcmsr_attr_host_fw_model(struct device *dev, struct device_attribute *attr,
struct Scsi_Host *host = class_to_shost(dev);
struct AdapterControlBlock *acb =
(struct AdapterControlBlock *) host->hostdata;
- return snprintf(buf, PAGE_SIZE,
- "%s\n",
- acb->firm_model);
+ return sysfs_emit(buf, "%s\n", acb->firm_model);
}

static ssize_t
@@ -319,9 +309,7 @@ arcmsr_attr_host_fw_version(struct device *dev,
struct AdapterControlBlock *acb =
(struct AdapterControlBlock *) host->hostdata;

- return snprintf(buf, PAGE_SIZE,
- "%s\n",
- acb->firm_version);
+ return sysfs_emit(buf, "%s\n", acb->firm_version);
}

static ssize_t
@@ -332,9 +320,7 @@ arcmsr_attr_host_fw_request_len(struct device *dev,
struct AdapterControlBlock *acb =
(struct AdapterControlBlock *) host->hostdata;

- return snprintf(buf, PAGE_SIZE,
- "%4d\n",
- acb->firm_request_len);
+ return sysfs_emit(buf, "%4d\n", acb->firm_request_len);
}

static ssize_t
@@ -345,9 +331,7 @@ arcmsr_attr_host_fw_numbers_queue(struct device *dev,
struct AdapterControlBlock *acb =
(struct AdapterControlBlock *) host->hostdata;

- return snprintf(buf, PAGE_SIZE,
- "%4d\n",
- acb->firm_numbers_queue);
+ return sysfs_emit(buf, "%4d\n", acb->firm_numbers_queue);
}

static ssize_t
@@ -358,9 +342,7 @@ arcmsr_attr_host_fw_sdram_size(struct device *dev,
struct AdapterControlBlock *acb =
(struct AdapterControlBlock *) host->hostdata;

- return snprintf(buf, PAGE_SIZE,
- "%4d\n",
- acb->firm_sdram_size);
+ return sysfs_emit(buf, "%4d\n", acb->firm_sdram_size);
}

static ssize_t
@@ -371,9 +353,7 @@ arcmsr_attr_host_fw_hd_channels(struct device *dev,
struct AdapterControlBlock *acb =
(struct AdapterControlBlock *) host->hostdata;

- return snprintf(buf, PAGE_SIZE,
- "%4d\n",
- acb->firm_hd_channels);
+ return sysfs_emit(buf, "%4d\n", acb->firm_hd_channels);
}

static DEVICE_ATTR(host_driver_version, S_IRUGO, arcmsr_attr_host_driver_version, NULL);
--
2.43.0.594.gd9cf4e227d-goog