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bpf: dispatch to sleepable file dynptr

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File dynptr reads may sleep when the requested folios are not in
the page cache. To avoid sleeping in non-sleepable contexts while still
supporting valid sleepable use, given that dynptrs are non-sleepable by
default, enable sleeping only when bpf_dynptr_from_file() is invoked
from a sleepable context.

This change:
  * Introduces a sleepable constructor: bpf_dynptr_from_file_sleepable()
  * Override non-sleepable constructor with sleepable if it's always
  called in sleepable context

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251026203853.135105-10-mykyta.yatsenko5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Mykyta Yatsenko
2025-10-26 20:38:52 +00:00
committed by Alexei Starovoitov
parent d869d56ca8
commit 2c52e8943a
3 changed files with 15 additions and 3 deletions
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5
kernel/bpf/helpers.c
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@@ -4336,6 +4336,11 @@ __bpf_kfunc int bpf_dynptr_from_file(struct file *file, u32 flags, struct bpf_dy
return make_file_dynptr(file, flags, false, (struct bpf_dynptr_kern *)ptr__uninit);
}
int bpf_dynptr_from_file_sleepable(struct file *file, u32 flags, struct bpf_dynptr *ptr__uninit)
{
return make_file_dynptr(file, flags, true, (struct bpf_dynptr_kern *)ptr__uninit);
}
__bpf_kfunc int bpf_dynptr_file_discard(struct bpf_dynptr *dynptr)
{
struct bpf_dynptr_kern *ptr = (struct bpf_dynptr_kern *)dynptr;