----- Original Message ----- > From: "David Binderman" <linuxdev.baldrick@xxxxxxxxx> > To: jejb@xxxxxxxxxxxxxxxxxx, "martin petersen" <martin.petersen@xxxxxxxxxx>, linux-scsi@xxxxxxxxxxxxxxx, "Linux > Kernel Mailing List" <linux-kernel@xxxxxxxxxxxxxxx>, dcb314@xxxxxxxxxxx > Sent: Monday, August 8, 2016 9:46:53 AM > Subject: linux-4.8-rc1/drivers/scsi/sd.c:317: pointless test ? > > Hello there, > > linux-4.8-rc1/drivers/scsi/sd.c:317]: (style) Unsigned variable 'val' > can't be negative so it is unnecessary to test it. > > Source code is > > if (val >= 0 && val <= SD_DIF_TYPE3_PROTECTION) > > but > > unsigned int val; > > Suggest new code > > if (val <= SD_DIF_TYPE3_PROTECTION) > > Regards > > David Binderman > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Hello Declaring val as unsigned does not prevent it from being assigned a negative integer. This means there is a possibility it could be negative. However looking at the code it seems that we are converting char *buf (string) to an int to set val here. Also the kernel code shows we cannot have a - sign anyway so I expect your suggestion should be fine to change this. static ssize_t protection_type_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct scsi_disk *sdkp = to_scsi_disk(dev); unsigned int val; int err; if (!capable(CAP_SYS_ADMIN)) return -EACCES; err = kstrtouint(buf, 10, &val); ***** if (err) return err; if (val >= 0 && val <= SD_DIF_TYPE3_PROTECTION) sdkp->protection_type = val; Reviewed-by Laurence Oberman <loberman@xxxxxxxxxx> return count; } /** * kstrtouint - convert a string to an unsigned int * @s: The start of the string. The string must be null-terminated, and may also * include a single newline before its terminating null. The first character * may also be a plus sign, but not a minus sign. * @base: The number base to use. The maximum supported base is 16. If base is * given as 0, then the base of the string is automatically detected with the * conventional semantics - If it begins with 0x the number will be parsed as a * hexadecimal (case insensitive), if it otherwise begins with 0, it will be * parsed as an octal number. Otherwise it will be parsed as a decimal. * @res: Where to write the result of the conversion on success. * * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error. * Used as a replacement for the obsolete simple_strtoull. Return code must * be checked. */ int kstrtouint(const char *s, unsigned int base, unsigned int *res) { unsigned long long tmp; int rv; rv = kstrtoull(s, base, &tmp); if (rv < 0) return rv; if (tmp != (unsigned long long)(unsigned int)tmp) return -ERANGE; *res = tmp; return 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
