Messages in this thread Patch in this message | | | Date | Thu, 1 Oct 2020 09:56:08 -0500 | From | "Gustavo A. R. Silva" <> | Subject | [PATCH v2][next] x86/uv/time: Replace one-element array and save heap space |
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There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use “flexible array members”[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2].
struct uv_rtc_timer_head contains a one-element array cpu[1].
Switch it to a flexible array and use the struct_size() helper to calculate the allocation size. Also, save some heap space in the process[3].
[1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arrays [3] https://lore.kernel.org/lkml/20200518190114.GA7757@embeddedor/
Reviewed-by: Kees Cook <keescook@chromium.org> Build-tested-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/lkml/5f75bc0a.rQcNS6620b2eA74S%25lkp@intel.com/ Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- Changes in v2: - Modify changelog text (Thomas). - Add Reviewed-by and Build-tested-by tags. - Add a public link to the build-test results.
arch/x86/platform/uv/uv_time.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/arch/x86/platform/uv/uv_time.c b/arch/x86/platform/uv/uv_time.c index f82a1337a608..6c348c2d0def 100644 --- a/arch/x86/platform/uv/uv_time.c +++ b/arch/x86/platform/uv/uv_time.c @@ -52,7 +52,7 @@ struct uv_rtc_timer_head { struct { int lcpu; /* systemwide logical cpu number */ u64 expires; /* next timer expiration for this cpu */ - } cpu[1]; + } cpu[]; }; /* @@ -148,9 +148,8 @@ static __init int uv_rtc_allocate_timers(void) struct uv_rtc_timer_head *head = blade_info[bid]; if (!head) { - head = kmalloc_node(sizeof(struct uv_rtc_timer_head) + - (uv_blade_nr_possible_cpus(bid) * - 2 * sizeof(u64)), + head = kmalloc_node(struct_size(head, cpu, + uv_blade_nr_possible_cpus(bid)), GFP_KERNEL, nid); if (!head) { uv_rtc_deallocate_timers(); -- 2.27.0
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