diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-driver-st | 12 | ||||
| -rw-r--r-- | Documentation/scsi/st.txt | 4 | ||||
| -rw-r--r-- | drivers/scsi/st.c | 30 |
3 files changed, 45 insertions, 1 deletions
diff --git a/Documentation/ABI/testing/sysfs-driver-st b/Documentation/ABI/testing/sysfs-driver-st new file mode 100644 index 000000000000..ba5d77008a85 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-driver-st @@ -0,0 +1,12 @@ +What: /sys/bus/scsi/drivers/st/debug_flag +Date: October 2015 +Kernel Version: ?.? +Contact: shane.seymour@hpe.com +Description: + This file allows you to turn debug output from the st driver + off if you write a '0' to the file or on if you write a '1'. + Note that debug output requires that the module be compiled + with the #define DEBUG set to a non-zero value (this is the + default). If DEBUG is set to 0 then this file will not + appear in sysfs as its presence is conditional upon debug + output support being compiled into the module. diff --git a/Documentation/scsi/st.txt b/Documentation/scsi/st.txt index f29fa550665a..b3211af63b79 100644 --- a/Documentation/scsi/st.txt +++ b/Documentation/scsi/st.txt @@ -569,7 +569,9 @@ Debugging code is now compiled in by default but debugging is turned off with the kernel module parameter debug_flag defaulting to 0. Debugging can still be switched on and off with an ioctl. To enable debug at module load time add debug_flag=1 to the module load options, the -debugging output is not voluminous. +debugging output is not voluminous. Debugging can also be enabled +and disabled by writing a '0' (disable) or '1' (enable) to the sysfs +file /sys/bus/scsi/drivers/st/debug_flag. If the tape seems to hang, I would be very interested to hear where the driver is waiting. With the command 'ps -l' you can see the state diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c index b37b9b00c4b4..e0a1e52a04e7 100644 --- a/drivers/scsi/st.c +++ b/drivers/scsi/st.c @@ -4452,11 +4452,41 @@ static ssize_t version_show(struct device_driver *ddd, char *buf) } static DRIVER_ATTR_RO(version); +#if DEBUG +static ssize_t debug_flag_store(struct device_driver *ddp, + const char *buf, size_t count) +{ +/* We only care what the first byte of the data is the rest is unused. + * if it's a '1' we turn on debug and if it's a '0' we disable it. All + * other values have -EINVAL returned if they are passed in. + */ + if (count > 0) { + if (buf[0] == '0') { + debugging = NO_DEBUG; + return count; + } else if (buf[0] == '1') { + debugging = 1; + return count; + } + } + return -EINVAL; +} + +static ssize_t debug_flag_show(struct device_driver *ddp, char *buf) +{ + return scnprintf(buf, PAGE_SIZE, "%d\n", debugging); +} +static DRIVER_ATTR_RW(debug_flag); +#endif + static struct attribute *st_drv_attrs[] = { &driver_attr_try_direct_io.attr, &driver_attr_fixed_buffer_size.attr, &driver_attr_max_sg_segs.attr, &driver_attr_version.attr, +#if DEBUG + &driver_attr_debug_flag.attr, +#endif NULL, }; ATTRIBUTE_GROUPS(st_drv); |