Messages in this thread | | | Subject | RE: [PATCH V3 4/4] x86/resctrl: Use appropriate API for strings terminated by newline | From | Babu Moger <> | Date | Thu, 14 May 2020 15:06:31 -0500 |
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> -----Original Message----- > From: Andy Shevchenko <andy.shevchenko@gmail.com> > Sent: Thursday, May 14, 2020 2:11 PM > To: Moger, Babu <Babu.Moger@amd.com> > Cc: Reinette Chatre <reinette.chatre@intel.com>; tglx@linutronix.de; > fenghua.yu@intel.com; bp@alien8.de; tony.luck@intel.com; kuo- > lang.tseng@intel.com; ravi.v.shankar@intel.com; mingo@redhat.com; > hpa@zytor.com; x86@kernel.org; linux-kernel@vger.kernel.org; Andy > Shevchenko <andriy.shevchenko@linux.intel.com> > Subject: Re: [PATCH V3 4/4] x86/resctrl: Use appropriate API for strings > terminated by newline > > On Thu, May 14, 2020 at 10:08 PM Babu Moger <babu.moger@amd.com> > wrote: > > > -----Original Message----- > > > From: Reinette Chatre <reinette.chatre@intel.com> > > > Sent: Wednesday, May 6, 2020 6:50 PM > > > To: tglx@linutronix.de; fenghua.yu@intel.com; bp@alien8.de; > > > tony.luck@intel.com > > > Cc: kuo-lang.tseng@intel.com; ravi.v.shankar@intel.com; > mingo@redhat.com; > > > Moger, Babu <Babu.Moger@amd.com>; hpa@zytor.com; x86@kernel.org; > > > linux-kernel@vger.kernel.org; Reinette Chatre <reinette.chatre@intel.com>; > > > Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > > Subject: [PATCH V3 4/4] x86/resctrl: Use appropriate API for strings > terminated > > > by newline > > > > > > 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 | 32 ++++++++++++++------------ > > > 1 file changed, 17 insertions(+), 15 deletions(-) > > > > > > diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c > > > b/arch/x86/kernel/cpu/resctrl/rdtgroup.c > > > index c60a3b307f7d..e70694892c02 100644 > > > --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c > > > +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c > > > @@ -1408,12 +1408,11 @@ static ssize_t rdtgroup_mode_write(struct > > > kernfs_open_file *of, > > > { > > > struct rdtgroup *rdtgrp; > > > enum rdtgrp_mode mode; > > > - int ret = 0; > > > + int user_m; > > > + int ret; > > > > This is bit confusing here. Mode and user_m should have been of same type. > > It can't. If you compare enum to int you will need the explicit (weird) casting.
Ok. Got it. That is fine then.
> > You can define user_m to user_mode to be very clear. > > > You can completely remove "mode" and directly use rdtgrp->mode instead. It > > is left to you. > > > > > > - /* Valid input requires a trailing newline */ > > > - if (nbytes == 0 || buf[nbytes - 1] != '\n') > > > + if (nbytes == 0) > > > return -EINVAL; > > > - buf[nbytes - 1] = '\0'; > > > > > > rdtgrp = rdtgroup_kn_lock_live(of->kn); > > > if (!rdtgrp) { > > > @@ -1425,11 +1424,17 @@ 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)) > > > + ret = sysfs_match_string(rdt_mode_str, buf); > > > + if (ret < 0) { > > > + rdt_last_cmd_puts("Unknown or unsupported mode\n"); > > > + goto out; > > > + } > > > + > > > + user_m = ret; > > > + ret = 0; > > > + > > > + /* Do nothing and return success if user asks for current mode */ > > > + if (user_m == mode) > > > goto out; > > > > > > if (mode == RDT_MODE_PSEUDO_LOCKED) { > > > @@ -1438,14 +1443,14 @@ 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; > > > @@ -1456,14 +1461,11 @@ 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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