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(unknown [IPv6:2a02:a03f:eaf9:8401:aa9f:5d01:1b2a:e3cd]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: sander@svanheule.net) by polaris.svanheule.net (Postfix) with ESMTPSA id 1FBBD2E2DA2; Sun, 5 Jun 2022 08:22:47 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=svanheule.net; s=mail1707; t=1654410167; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=B2PsbTSzMFRa3tyPILmOXv9dgA1FxVSPhNZx0CHBfy0=; b=sF4xPDC9G4yDNXhqzUbkFfKUg9R3JTWuiemiwN3WWKhjGzslMkvxwA7kgk+PWEVYbROfN6 9yv84tV6yXfkiPTcipIue2eCFHduOuYF5O66yJWi0v56clh/+USZesE2iwknIRLwN2Jlcg 9sL9/tQhPg+CjAzOp2exqHLtacuKCtgKbILMqCKYhpJ12kvXQsYDYh0uXc/H3eJHCNdvVg lkEO3FTKYO3vS4jSRFcQJ3Oes6Z7Q1d9FFNH9sI/FzvoSk12IMj2jdkX7D/xnVcOMa9jwm n/600jmZgsC4rSn1LSI4Sg2CrvjwebJvUTpyBgmSxhmoQ2991hdozbUIDH6SIQ== From: Sander Vanheule To: Peter Zijlstra , Yury Norov , Andrew Morton , Valentin Schneider , Thomas Gleixner , Greg Kroah-Hartman , Marco Elver Cc: linux-kernel@vger.kernel.org, Andy Shevchenko , Sander Vanheule Subject: [PATCH v3 1/4] cpumask: Fix invalid uniprocessor mask assumption Date: Sun, 5 Jun 2022 08:22:38 +0200 Message-Id: X-Mailer: git-send-email 2.36.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On uniprocessor builds, any CPU mask is assumed to contain exactly one CPU (cpu0). This assumption ignores the existence of empty masks, resulting in incorrect behaviour. cpumask_first_zero(), cpumask_next_zero(), and for_each_cpu_not() don't provide behaviour matching the assumption that a UP mask is always "1", and instead provide behaviour matching the empty mask. Drop the incorrectly optimised code and use the generic implementations in all cases. Signed-off-by: Sander Vanheule --- Changes since v1: - Drop UP implementations instead of trying to fix them --- include/linux/cpumask.h | 80 ----------------------------------------- lib/Makefile | 3 +- 2 files changed, 1 insertion(+), 82 deletions(-) diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index fe29ac7cc469..d6add0e29ef4 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -116,85 +116,6 @@ static __always_inline unsigned int cpumask_check(unsigned int cpu) return cpu; } -#if NR_CPUS == 1 -/* Uniprocessor. Assume all masks are "1". */ -static inline unsigned int cpumask_first(const struct cpumask *srcp) -{ - return 0; -} - -static inline unsigned int cpumask_first_zero(const struct cpumask *srcp) -{ - return 0; -} - -static inline unsigned int cpumask_first_and(const struct cpumask *srcp1, - const struct cpumask *srcp2) -{ - return 0; -} - -static inline unsigned int cpumask_last(const struct cpumask *srcp) -{ - return 0; -} - -/* Valid inputs for n are -1 and 0. */ -static inline unsigned int cpumask_next(int n, const struct cpumask *srcp) -{ - return n+1; -} - -static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp) -{ - return n+1; -} - -static inline unsigned int cpumask_next_and(int n, - const struct cpumask *srcp, - const struct cpumask *andp) -{ - return n+1; -} - -static inline unsigned int cpumask_next_wrap(int n, const struct cpumask *mask, - int start, bool wrap) -{ - /* cpu0 unless stop condition, wrap and at cpu0, then nr_cpumask_bits */ - return (wrap && n == 0); -} - -/* cpu must be a valid cpu, ie 0, so there's no other choice. */ -static inline unsigned int cpumask_any_but(const struct cpumask *mask, - unsigned int cpu) -{ - return 1; -} - -static inline unsigned int cpumask_local_spread(unsigned int i, int node) -{ - return 0; -} - -static inline int cpumask_any_and_distribute(const struct cpumask *src1p, - const struct cpumask *src2p) { - return cpumask_first_and(src1p, src2p); -} - -static inline int cpumask_any_distribute(const struct cpumask *srcp) -{ - return cpumask_first(srcp); -} - -#define for_each_cpu(cpu, mask) \ - for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask) -#define for_each_cpu_not(cpu, mask) \ - for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask) -#define for_each_cpu_wrap(cpu, mask, start) \ - for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask, (void)(start)) -#define for_each_cpu_and(cpu, mask1, mask2) \ - for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask1, (void)mask2) -#else /** * cpumask_first - get the first cpu in a cpumask * @srcp: the cpumask pointer @@ -324,7 +245,6 @@ extern int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool for ((cpu) = -1; \ (cpu) = cpumask_next_and((cpu), (mask1), (mask2)), \ (cpu) < nr_cpu_ids;) -#endif /* SMP */ #define CPU_BITS_NONE \ { \ diff --git a/lib/Makefile b/lib/Makefile index 89fcae891361..6f26a429115b 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -34,10 +34,9 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \ is_single_threaded.o plist.o decompress.o kobject_uevent.o \ earlycpio.o seq_buf.o siphash.o dec_and_lock.o \ nmi_backtrace.o nodemask.o win_minmax.o memcat_p.o \ - buildid.o + buildid.o cpumask.o lib-$(CONFIG_PRINTK) += dump_stack.o -lib-$(CONFIG_SMP) += cpumask.o lib-y += kobject.o klist.o obj-y += lockref.o -- 2.36.1