Messages in this thread Patch in this message |  | | Date | Thu, 2 Apr 2020 16:06:25 +0300 | From | Andy Shevchenko <> | Subject | Re: [PATCH 2/2] x86/resctrl: Use appropriate API for strings terminated by newline |
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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; >
> /* 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.
> 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;
> + /* Do nothing and return success if user asks for current mode */ > + if (user_m == mode) > goto out; > > if (mode == RDT_MODE_PSEUDO_LOCKED) { > @@ -1441,14 +1445,14 @@ static ssize_t rdtgroup_mode_write(struct kernfs_open_file *of, > goto out; > } > > - if (!strcmp(buf, "shareable")) { > + if (user_m == RDT_MODE_SHAREABLE) { > if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) { > ret = rdtgroup_locksetup_exit(rdtgrp); > if (ret) > goto out; > } > rdtgrp->mode = RDT_MODE_SHAREABLE; > - } else if (!strcmp(buf, "exclusive")) { > + } else if (user_m == RDT_MODE_EXCLUSIVE) { > if (!rdtgroup_mode_test_exclusive(rdtgrp)) { > ret = -EINVAL; > goto out; > @@ -1459,14 +1463,11 @@ static ssize_t rdtgroup_mode_write(struct kernfs_open_file *of, > goto out; > } > rdtgrp->mode = RDT_MODE_EXCLUSIVE; > - } else if (!strcmp(buf, "pseudo-locksetup")) { > + } else if (user_m == RDT_MODE_PSEUDO_LOCKSETUP) { > ret = rdtgroup_locksetup_enter(rdtgrp); > if (ret) > goto out; > rdtgrp->mode = RDT_MODE_PSEUDO_LOCKSETUP; > - } else { > - rdt_last_cmd_puts("Unknown or unsupported mode\n"); > - ret = -EINVAL; > } > > out: > -- > 2.21.0 >
-- With Best Regards, Andy Shevchenko
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