Messages in this thread |  | | Subject | Re: [PATCH 2/2] x86/resctrl: Use appropriate API for strings terminated by newline | From | Reinette Chatre <> | Date | Thu, 2 Apr 2020 14:19:07 -0700 |
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Hi Andy,
(Your two responses have been merged)
On 4/2/2020 6:06 AM, Andy Shevchenko wrote: > On Wed, Apr 01, 2020 at 11:30:48AM -0700, Reinette Chatre wrote: >> The user input to files in the resctrl filesystem are expected to be >> terminated with a newline. Testing the user input includes a test for >> the presence of a newline and then replacing the newline with NUL >> byte followed by comparison using strcmp(). >> >> sysfs_streq() exists to test if strings are equal, treating both NUL and >> newline-then-NUL as equivalent string terminations. Even more, >> sysfs_match_string() exists to match a given string in an array using >> sysfs_streq(). >> >> Replace existing strcmp() comparisons of strings that are terminated >> with a newline with more appropriate sysfs_streq() via the >> sysfs_match_string() API that can perform the match across the different >> mode strings that are already maintained in an array. >> >> Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> >> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> >> --- >> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 25 +++++++++++++------------ >> 1 file changed, 13 insertions(+), 12 deletions(-) >> >> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c >> index fbee891a7d6e..623e33c0a290 100644 >> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c >> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c >> @@ -1412,11 +1412,11 @@ static ssize_t rdtgroup_mode_write(struct kernfs_open_file *of, >> struct rdtgroup *rdtgrp; >> enum rdtgrp_mode mode; >> int ret = 0; >> + int user_m; >>
> > ...and forgot to mention this... > > int user_m; > int ret; >
> >> /* Valid input requires a trailing newline */ >> if (nbytes == 0 || buf[nbytes - 1] != '\n') >> return -EINVAL; >> - buf[nbytes - 1] = '\0'; > > The above test is not needed and comment now is misleading. > WRT nbytes I believe that kernel fs code checks for that.
If nbytes is 0 it is still passed to this function. You are correct that those tests are not needed though (if nbytes is 0 then sysfs_match_string() will not find a match and return EINVAL via that path).
Thank you for catching this. I'll remove those unnecessary checks.
> >> rdtgrp = rdtgroup_kn_lock_live(of->kn); >> if (!rdtgrp) { >> @@ -1428,11 +1428,15 @@ static ssize_t rdtgroup_mode_write(struct kernfs_open_file *of, >> >> mode = rdtgrp->mode; >> >> - if ((!strcmp(buf, "shareable") && mode == RDT_MODE_SHAREABLE) || >> - (!strcmp(buf, "exclusive") && mode == RDT_MODE_EXCLUSIVE) || >> - (!strcmp(buf, "pseudo-locksetup") && >> - mode == RDT_MODE_PSEUDO_LOCKSETUP) || >> - (!strcmp(buf, "pseudo-locked") && mode == RDT_MODE_PSEUDO_LOCKED)) >> + user_m = sysfs_match_string(rdt_mode_str, buf); >> + if (user_m < 0) { >> + rdt_last_cmd_puts("Unknown or unsupported mode\n"); >> + ret = user_m; >> + goto out; >> + } > > You can do it the way > > ret = sysfs_match_string(...); > if (ret < 0) { > ... > } > user_m = ret; > > ...and this changes > > ret = 0; > >
ok, I'll do it this way in the next version.
Thank you
Reinette
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