Re: [PATCH 16/39] convert __bpf_prog_get() to CLASS(fd, ...)
From: Andrii Nakryiko <hidden>
Date: 2024-08-06 21:08:39
Also in:
bpf, cgroups, kvm, linux-fsdevel
On Mon, Jul 29, 2024 at 10:19 PM [off-list ref] wrote:
From: Al Viro <viro@zeniv.linux.org.uk> Irregularity here is fdput() not in the same scope as fdget(); just fold ____bpf_prog_get() into its (only) caller and that's it... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> --- kernel/bpf/syscall.c | 32 +++++++++++--------------------- 1 file changed, 11 insertions(+), 21 deletions(-)
Folding makes total sense, the logic lgtm (though I find CLASS(fd, f)(ufd) utterly non-intuitive naming-wise). Extra IS_ERR(prog) check should be dropped though, see below. Acked-by: Andrii Nakryiko <andrii@kernel.org>
quoted hunk ↗ jump to hunk
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 3093bf2cc266..c5b252c0faa8 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c@@ -2407,18 +2407,6 @@ int bpf_prog_new_fd(struct bpf_prog *prog) O_RDWR | O_CLOEXEC); } -static struct bpf_prog *____bpf_prog_get(struct fd f) -{ - if (!fd_file(f)) - return ERR_PTR(-EBADF); - if (fd_file(f)->f_op != &bpf_prog_fops) { - fdput(f); - return ERR_PTR(-EINVAL); - } - - return fd_file(f)->private_data; -} - void bpf_prog_add(struct bpf_prog *prog, int i) { atomic64_add(i, &prog->aux->refcnt);@@ -2474,20 +2462,22 @@ bool bpf_prog_get_ok(struct bpf_prog *prog, static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *attach_type, bool attach_drv) { - struct fd f = fdget(ufd); + CLASS(fd, f)(ufd); struct bpf_prog *prog; - prog = ____bpf_prog_get(f); - if (IS_ERR(prog)) + if (fd_empty(f)) + return ERR_PTR(-EBADF); + if (fd_file(f)->f_op != &bpf_prog_fops) + return ERR_PTR(-EINVAL); + + prog = fd_file(f)->private_data; + if (IS_ERR(prog)) // can that actually happen?
no, it can't, private_data will always be a valid pointer, otherwise that file would never be successfully created
return prog;
- if (!bpf_prog_get_ok(prog, attach_type, attach_drv)) {
- prog = ERR_PTR(-EINVAL);
- goto out;
- }
+
+ if (!bpf_prog_get_ok(prog, attach_type, attach_drv))
+ return ERR_PTR(-EINVAL);
bpf_prog_inc(prog);
-out:
- fdput(f);
return prog;
}
--
2.39.2