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| author | Xu Kuohai <xukuohai@huawei.com> | 2022-11-10 13:21:28 +0100 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2022-11-11 21:05:14 +0100 |
| commit | 4b45cd81f737d79d0fbfc0d320a1e518e7f0bbf0 (patch) | |
| tree | 29b8acb33922e5d8489342c09dfecc6cb0fe539f /kernel | |
| parent | Merge branch 'Fix offset when fault occurs in strncpy_from_kernel_nofault()' (diff) | |
| download | linux-4b45cd81f737d79d0fbfc0d320a1e518e7f0bbf0.tar.xz linux-4b45cd81f737d79d0fbfc0d320a1e518e7f0bbf0.zip | |
bpf: Initialize same number of free nodes for each pcpu_freelist
pcpu_freelist_populate() initializes nr_elems / num_possible_cpus() + 1
free nodes for some CPUs, and then possibly one CPU with fewer nodes,
followed by remaining cpus with 0 nodes. For example, when nr_elems == 256
and num_possible_cpus() == 32, CPU 0~27 each gets 9 free nodes, CPU 28 gets
4 free nodes, CPU 29~31 get 0 free nodes, while in fact each CPU should get
8 nodes equally.
This patch initializes nr_elems / num_possible_cpus() free nodes for each
CPU firstly, then allocates the remaining free nodes by one for each CPU
until no free nodes left.
Fixes: e19494edab82 ("bpf: introduce percpu_freelist")
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20221110122128.105214-1-xukuohai@huawei.com
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/percpu_freelist.c | 23 |
1 files changed, 11 insertions, 12 deletions
diff --git a/kernel/bpf/percpu_freelist.c b/kernel/bpf/percpu_freelist.c index b6e7f5c5b9ab..034cf87b54e9 100644 --- a/kernel/bpf/percpu_freelist.c +++ b/kernel/bpf/percpu_freelist.c @@ -100,22 +100,21 @@ void pcpu_freelist_populate(struct pcpu_freelist *s, void *buf, u32 elem_size, u32 nr_elems) { struct pcpu_freelist_head *head; - int i, cpu, pcpu_entries; + unsigned int cpu, cpu_idx, i, j, n, m; - pcpu_entries = nr_elems / num_possible_cpus() + 1; - i = 0; + n = nr_elems / num_possible_cpus(); + m = nr_elems % num_possible_cpus(); + cpu_idx = 0; for_each_possible_cpu(cpu) { -again: head = per_cpu_ptr(s->freelist, cpu); - /* No locking required as this is not visible yet. */ - pcpu_freelist_push_node(head, buf); - i++; - buf += elem_size; - if (i == nr_elems) - break; - if (i % pcpu_entries) - goto again; + j = n + (cpu_idx < m ? 1 : 0); + for (i = 0; i < j; i++) { + /* No locking required as this is not visible yet. */ + pcpu_freelist_push_node(head, buf); + buf += elem_size; + } + cpu_idx++; } } |