From: Kees Cook <keescook@chromium.org>
To: linux-kernel@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
Alexander Potapenko <glider@google.com>,
Joe Perches <joe@perches.com>, Andy Whitcroft <apw@canonical.com>,
x86@kernel.org, drbd-dev@lists.linbit.com,
linux-block@vger.kernel.org, b43-dev@lists.infradead.org,
netdev@vger.kernel.org, linux-doc@vger.kernel.org,
linux-wireless@vger.kernel.org, linux-ide@vger.kernel.org,
linux-clk@vger.kernel.org, linux-spi@vger.kernel.org,
linux-mm@kvack.org, clang-built-linux@googlegroups.com
Subject: [PATCH v2 02/16] x86/mm/numa: Remove uninitialized_var() usage
Date: Fri, 19 Jun 2020 20:29:53 -0700 [thread overview]
Message-ID: <20200620033007.1444705-3-keescook@chromium.org> (raw)
In-Reply-To: <20200620033007.1444705-1-keescook@chromium.org>
Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings (e.g.
"unused variable"). If the compiler thinks it is uninitialized, either
simply initialize the variable or make compiler changes. As a precursor
to removing[2] this[3] macro[4], refactor code to avoid its need.
The original reason for its use here was to work around the #ifdef
being the only place the variable was used. This is better expressed
using IS_ENABLED() and a new code block where the variable can be used
unconditionally.
[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
Fixes: 1e01979c8f50 ("x86, numa: Implement pfn -> nid mapping granularity check")
Signed-off-by: Kees Cook <keescook@chromium.org>
---
arch/x86/mm/numa.c | 18 +++++++++---------
include/linux/page-flags-layout.h | 4 +++-
2 files changed, 12 insertions(+), 10 deletions(-)
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 8ee952038c80..b05f45e5e8e2 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -543,7 +543,6 @@ static void __init numa_clear_kernel_node_hotplug(void)
static int __init numa_register_memblks(struct numa_meminfo *mi)
{
- unsigned long uninitialized_var(pfn_align);
int i, nid;
/* Account for nodes with cpus and no memory */
@@ -571,15 +570,16 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
* If sections array is gonna be used for pfn -> nid mapping, check
* whether its granularity is fine enough.
*/
-#ifdef NODE_NOT_IN_PAGE_FLAGS
- pfn_align = node_map_pfn_alignment();
- if (pfn_align && pfn_align < PAGES_PER_SECTION) {
- printk(KERN_WARNING "Node alignment %LuMB < min %LuMB, rejecting NUMA config\n",
- PFN_PHYS(pfn_align) >> 20,
- PFN_PHYS(PAGES_PER_SECTION) >> 20);
- return -EINVAL;
+ if (IS_ENABLED(NODE_NOT_IN_PAGE_FLAGS)) {
+ unsigned long pfn_align = node_map_pfn_alignment();
+
+ if (pfn_align && pfn_align < PAGES_PER_SECTION) {
+ pr_warn("Node alignment %LuMB < min %LuMB, rejecting NUMA config\n",
+ PFN_PHYS(pfn_align) >> 20,
+ PFN_PHYS(PAGES_PER_SECTION) >> 20);
+ return -EINVAL;
+ }
}
-#endif
if (!numa_meminfo_cover_memory(mi))
return -EINVAL;
diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h
index 71283739ffd2..e200eef6a7fd 100644
--- a/include/linux/page-flags-layout.h
+++ b/include/linux/page-flags-layout.h
@@ -98,9 +98,11 @@
/*
* We are going to use the flags for the page to node mapping if its in
* there. This includes the case where there is no node, so it is implicit.
+ * Note that this #define MUST have a value so that it can be tested with
+ * the IS_ENABLED() macro.
*/
#if !(NODES_WIDTH > 0 || NODES_SHIFT == 0)
-#define NODE_NOT_IN_PAGE_FLAGS
+#define NODE_NOT_IN_PAGE_FLAGS 1
#endif
#if defined(CONFIG_NUMA_BALANCING) && LAST_CPUPID_WIDTH == 0
--
2.25.1
next prev parent reply other threads:[~2020-06-20 3:33 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-20 3:29 [PATCH v2 00/16] Remove uninitialized_var() macro Kees Cook
2020-06-20 3:29 ` [PATCH v2 01/16] docs: deprecated.rst: Add uninitialized_var() Kees Cook
2020-06-22 16:59 ` Nick Desaulniers
2020-06-20 3:29 ` Kees Cook [this message]
2020-06-20 3:29 ` [PATCH v2 03/16] drbd: Remove uninitialized_var() usage Kees Cook
2020-06-20 3:29 ` [PATCH v2 04/16] b43: " Kees Cook
2020-06-22 17:04 ` Nick Desaulniers
2020-06-22 21:04 ` Kees Cook
2020-06-23 18:29 ` Nick Desaulniers
2020-07-15 10:37 ` Kalle Valo
2020-06-20 3:29 ` [PATCH v2 05/16] rtlwifi: rtl8192cu: " Kees Cook
2020-06-20 3:29 ` [PATCH v2 06/16] ide: " Kees Cook
2020-06-20 3:29 ` [PATCH v2 07/16] clk: st: " Kees Cook
2020-06-22 9:03 ` Stephen Boyd
2020-06-20 3:29 ` [PATCH v2 08/16] spi: davinci: " Kees Cook
2020-07-01 20:39 ` Mark Brown
2020-07-02 15:21 ` Kees Cook
2020-07-02 15:23 ` Mark Brown
2020-07-02 15:42 ` Kees Cook
2020-07-02 16:23 ` Joe Perches
2020-06-20 3:30 ` [PATCH v2 09/16] clk: spear: " Kees Cook
2020-06-22 9:03 ` Stephen Boyd
2020-06-20 3:30 ` [PATCH v2 10/16] KVM: PPC: Book3S PR: " Kees Cook
2020-06-22 17:22 ` Nick Desaulniers
2020-06-20 3:30 ` [PATCH v2 11/16] media: sur40: " Kees Cook
2020-06-22 18:39 ` Nick Desaulniers
2020-06-20 3:30 ` [PATCH v2 12/16] f2fs: Eliminate usage of uninitialized_var() macro Kees Cook
2020-06-20 3:30 ` [PATCH v2 14/16] checkpatch: Remove awareness " Kees Cook
2020-06-20 3:30 ` [PATCH v2 15/16] treewide: Remove uninitialized_var() usage Kees Cook
2020-06-20 3:30 ` [PATCH v2 16/16] compiler: Remove uninitialized_var() macro Kees Cook
2020-06-20 3:30 ` [PATCH v2 13/16] mm/debug_vm_pgtable: Remove uninitialized_var() usage Kees Cook
2020-06-22 17:27 ` Nick Desaulniers
2020-06-20 7:03 ` [PATCH v2 00/16] Remove uninitialized_var() macro Sedat Dilek
2020-06-20 15:57 ` Kees Cook
2020-06-22 9:07 ` Sedat Dilek
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