Messages in this thread Patch in this message | | | Subject | Error returns not handled correctly by sysfs.c:subsys_attr_store() | From | Andrew Patterson <> | Date | Wed, 21 Nov 2007 15:16:59 -0700 |
| |
The buf in fs/sysfs.c:subsys_attr_store() does not seem to be updated correctly when returning a negative value (indicating that an error condition has occurred) is returned. If a negative value is returned, the next subsequent call to subsys_attr_store will have the contents of buf appended to the previous call. Example: I have modified the sd.c:sd_store_allow_restart to always print out the contents of the buf and return an error using the following patch:
--- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -183,6 +183,9 @@ static ssize_t sd_store_allow_restart(struct class_device *c struct scsi_disk *sdkp = to_scsi_disk(cdev); struct scsi_device *sdp = sdkp->device; + printk(KERN_ERR "buf_ptr = 0x%p, buf = %s, count = %u\n", buf, buf, coun + return -EINVAL; + if (!capable(CAP_SYS_ADMIN)) return -EACCES;
I get the following output when writing invalid values to the allow_restart sysfs file: # echo x > /sys/class/scsi_disk/4:0:0:0/allow_restart bash: echo: write error: Invalid argument # echo y > /sys/class/scsi_disk/4:0:0:0/allow_restart bash: echo: write error: Invalid argument # echo z > /sys/class/scsi_disk/4:0:0:0/allow_restart bash: echo: write error: Invalid argument And the console output shows:
buf_ptr = 0xe00001004bdb0000, buf = x , count = 2 buf_ptr = 0xe00001004bdb0000, buf = x , count = 2 buf_ptr = 0xe00001004bdb0000, buf = x y , count = 4 buf_ptr = 0xe00001004bdb0000, buf = x y , count = 4 buf_ptr = 0xe00001004caf0000, buf = x y z , count = 6 buf_ptr = 0xe00001004caf0000, buf = x y z , count = 6 and the same append problem occurs when using another sysfs file:
# echo xyzzy > /sys/class/scsi_disk/4:0:1:0/allow_restart bash: echo: write error: Invalid argument buf_ptr = 0xe00001004caf0000, buf = x y z xyzzy , count = 12 I found this problem in 2.6.24-rc3 and and an earlier version of 2.6.23.
This seems to work correctly on 2.6.18 (at least with the RHEL5 kernel I did some testing with), i.e. the contents of buf from the previous failed called are thrown away/overwritten. I looked through sysfs.c to see if I could find anything obvious but could not see anything. Perhaps this is handled at a higher level.
-- Andrew Patterson Hewlett-Packard
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |