Messages in this thread Patch in this message | | | Date | Wed, 24 Jan 2024 08:58:27 -0600 | Subject | Re: [tip:x86/cache 3/3] arch/x86/kernel/cpu/resctrl/rdtgroup.c:1621:5-8: Unneeded variable: "ret". Return " 0" on line 1655 | From | "Moger, Babu" <> |
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Hi Boris,
On 1/24/24 04:55, Borislav Petkov wrote: > On Wed, Jan 24, 2024 at 06:31:41PM +0800, kernel test robot wrote: >> tree: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/cache >> head: 54e35eb8611cce5550d3d7689679b1a91c864f28 >> commit: 54e35eb8611cce5550d3d7689679b1a91c864f28 [3/3] x86/resctrl: Read supported bandwidth sources from CPUID >> config: x86_64-randconfig-102-20240124 (https://download.01.org/0day-ci/archive/20240124/202401241810.jbd8Ipa1-lkp@intel.com/config) >> compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18) >> >> If you fix the issue in a separate patch/commit (i.e. not just a new version of >> the same patch/commit), kindly add following tags >> | Reported-by: kernel test robot <lkp@intel.com> >> | Closes: https://lore.kernel.org/oe-kbuild-all/202401241810.jbd8Ipa1-lkp@intel.com/ >> >> cocci warnings: (new ones prefixed by >>) >>>> arch/x86/kernel/cpu/resctrl/rdtgroup.c:1621:5-8: Unneeded variable: "ret". Return " 0" on line 1655
Hmm Interesting..
Looking at the code, I see the ret variable is really not required.
The following patch should fix the problem. Let me know if you want me to send the patch officially. Thanks
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index 2b69e560b05f..6057f96df73f 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -1618,7 +1618,6 @@ static int mbm_config_write_domain(struct rdt_resource *r, struct rdt_domain *d, u32 evtid, u32 val) { struct mon_config_info mon_info = {0}; - int ret = 0;
/* * Read the current config value first. If both are the same then @@ -1652,7 +1651,7 @@ static int mbm_config_write_domain(struct rdt_resource *r, resctrl_arch_reset_rmid_all(r, d);
out: - return ret; + return 0; }
static int mon_config_write(struct rdt_resource *r, char *tok, u32 evtid) > > Well, AFAICT, even with the tree checked out at > > 92bd5a139033 ("x86/resctrl: Add interface to write mbm_total_bytes_config") > > which is the first patch that added this function, ret is unneeded. > > But scripts/coccinelle/misc/returnvar.cocci doesn't warn about it then, > only now that that hunk with the "return -EINVAL;" is removed in the > patch you're reporting this against. > > Lemme add some cocci people to Cc for comment and leave the rest for > reference. > > Thx. > >> vim +1621 arch/x86/kernel/cpu/resctrl/rdtgroup.c >> >> 92bd5a1390335b Babu Moger 2023-01-13 1616 >> 92bd5a1390335b Babu Moger 2023-01-13 1617 static int mbm_config_write_domain(struct rdt_resource *r, >> 92bd5a1390335b Babu Moger 2023-01-13 1618 struct rdt_domain *d, u32 evtid, u32 val) >> 92bd5a1390335b Babu Moger 2023-01-13 1619 { >> 92bd5a1390335b Babu Moger 2023-01-13 1620 struct mon_config_info mon_info = {0}; >> 92bd5a1390335b Babu Moger 2023-01-13 @1621 int ret = 0; >> 92bd5a1390335b Babu Moger 2023-01-13 1622 >> 92bd5a1390335b Babu Moger 2023-01-13 1623 /* >> 92bd5a1390335b Babu Moger 2023-01-13 1624 * Read the current config value first. If both are the same then >> 92bd5a1390335b Babu Moger 2023-01-13 1625 * no need to write it again. >> 92bd5a1390335b Babu Moger 2023-01-13 1626 */ >> 92bd5a1390335b Babu Moger 2023-01-13 1627 mon_info.evtid = evtid; >> 92bd5a1390335b Babu Moger 2023-01-13 1628 mondata_config_read(d, &mon_info); >> 92bd5a1390335b Babu Moger 2023-01-13 1629 if (mon_info.mon_config == val) >> 92bd5a1390335b Babu Moger 2023-01-13 1630 goto out; >> 92bd5a1390335b Babu Moger 2023-01-13 1631 >> 92bd5a1390335b Babu Moger 2023-01-13 1632 mon_info.mon_config = val; >> 92bd5a1390335b Babu Moger 2023-01-13 1633 >> 92bd5a1390335b Babu Moger 2023-01-13 1634 /* >> 92bd5a1390335b Babu Moger 2023-01-13 1635 * Update MSR_IA32_EVT_CFG_BASE MSR on one of the CPUs in the >> 92bd5a1390335b Babu Moger 2023-01-13 1636 * domain. The MSRs offset from MSR MSR_IA32_EVT_CFG_BASE >> 92bd5a1390335b Babu Moger 2023-01-13 1637 * are scoped at the domain level. Writing any of these MSRs >> 92bd5a1390335b Babu Moger 2023-01-13 1638 * on one CPU is observed by all the CPUs in the domain. >> 92bd5a1390335b Babu Moger 2023-01-13 1639 */ >> 92bd5a1390335b Babu Moger 2023-01-13 1640 smp_call_function_any(&d->cpu_mask, mon_event_config_write, >> 92bd5a1390335b Babu Moger 2023-01-13 1641 &mon_info, 1); >> 92bd5a1390335b Babu Moger 2023-01-13 1642 >> 92bd5a1390335b Babu Moger 2023-01-13 1643 /* >> 92bd5a1390335b Babu Moger 2023-01-13 1644 * When an Event Configuration is changed, the bandwidth counters >> 92bd5a1390335b Babu Moger 2023-01-13 1645 * for all RMIDs and Events will be cleared by the hardware. The >> 92bd5a1390335b Babu Moger 2023-01-13 1646 * hardware also sets MSR_IA32_QM_CTR.Unavailable (bit 62) for >> 92bd5a1390335b Babu Moger 2023-01-13 1647 * every RMID on the next read to any event for every RMID. >> 92bd5a1390335b Babu Moger 2023-01-13 1648 * Subsequent reads will have MSR_IA32_QM_CTR.Unavailable (bit 62) >> 92bd5a1390335b Babu Moger 2023-01-13 1649 * cleared while it is tracked by the hardware. Clear the >> 92bd5a1390335b Babu Moger 2023-01-13 1650 * mbm_local and mbm_total counts for all the RMIDs. >> 92bd5a1390335b Babu Moger 2023-01-13 1651 */ >> 92bd5a1390335b Babu Moger 2023-01-13 1652 resctrl_arch_reset_rmid_all(r, d); >> 92bd5a1390335b Babu Moger 2023-01-13 1653 >> 92bd5a1390335b Babu Moger 2023-01-13 1654 out: >> 92bd5a1390335b Babu Moger 2023-01-13 @1655 return ret; >> 92bd5a1390335b Babu Moger 2023-01-13 1656 } >> 92bd5a1390335b Babu Moger 2023-01-13 1657 >> >> :::::: The code at line 1621 was first introduced by commit >> :::::: 92bd5a1390335bb3cc76bdf1b4356edbc94d408d x86/resctrl: Add interface to write mbm_total_bytes_config >> >> :::::: TO: Babu Moger <babu.moger@amd.com> >> :::::: CC: Borislav Petkov (AMD) <bp@alien8.de> >> >> -- >> 0-DAY CI Kernel Test Service >> https://github.com/intel/lkp-tests/wiki >
-- Thanks Babu Moger
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