From: Martin KaFai Lau <martin.lau@linux.dev>
To: Song Liu <song@kernel.org>
Cc: bpf@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org, kernel-team@meta.com,
andrii@kernel.org, eddyz87@gmail.com, ast@kernel.org,
daniel@iogearbox.net, viro@zeniv.linux.org.uk,
brauner@kernel.org, jack@suse.cz, kpsingh@kernel.org,
mattbobrowski@google.com, amir73il@gmail.com, repnop@google.com,
jlayton@kernel.org, josef@toxicpanda.com, mic@digikod.net,
gnoack@google.com
Subject: Re: [PATCH v2 bpf-next 2/4] bpf: Make bpf inode storage available to tracing program
Date: Tue, 12 Nov 2024 15:00:48 -0800 [thread overview]
Message-ID: <2cb0cd4f-5d78-4b7f-b280-2a3377ffbc21@linux.dev> (raw)
In-Reply-To: <20241112083700.356299-3-song@kernel.org>
On 11/12/24 12:36 AM, Song Liu wrote:
> void __destroy_inode(struct inode *inode)
> {
> BUG_ON(inode_has_buffers(inode));
> + bpf_inode_storage_free(inode);
Not sure if this is done in the rcu callback (i.e. after the rcu gp). Please check.
> inode_detach_wb(inode);
> security_inode_free(inode);
> fsnotify_inode_delete(inode);
[ ... ]
> @@ -136,12 +119,7 @@ BPF_CALL_5(bpf_inode_storage_get, struct bpf_map *, map, struct inode *, inode,
> if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
> return (unsigned long)NULL;
>
> - /* explicitly check that the inode_storage_ptr is not
> - * NULL as inode_storage_lookup returns NULL in this case and
> - * bpf_local_storage_update expects the owner to have a
> - * valid storage pointer.
> - */
> - if (!inode || !inode_storage_ptr(inode))
> + if (!inode)
> return (unsigned long)NULL;
There is an atomic_read in this function:
/* only allocate new storage, when the inode is refcounted */
if (atomic_read(&inode->i_count) &&
flags & BPF_LOCAL_STORAGE_GET_F_CREATE) {
If the bpf_inode_storage_free is not done after rcu gp, this will need a
inc_not_zero like how the sk storage does. I think moving the storage_free to
the inode rcu call back may be easier if it is not the case now.
next prev parent reply other threads:[~2024-11-12 23:00 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-12 8:36 [PATCH v2 bpf-next 0/4] Make inode storage available to tracing prog Song Liu
2024-11-12 8:36 ` [PATCH v2 bpf-next 1/4] bpf: lsm: Remove hook to bpf_task_storage_free Song Liu
2024-11-12 8:36 ` [PATCH v2 bpf-next 2/4] bpf: Make bpf inode storage available to tracing program Song Liu
2024-11-12 22:04 ` Alexei Starovoitov
2024-11-12 23:00 ` Martin KaFai Lau [this message]
2024-11-12 23:10 ` Song Liu
2024-11-12 8:36 ` [PATCH v2 bpf-next 3/4] bpf: Add recursion prevention logic for inode storage Song Liu
2024-11-12 23:26 ` Martin KaFai Lau
2024-11-12 8:37 ` [PATCH v2 bpf-next 4/4] selftest/bpf: Test inode local storage recursion prevention Song Liu
2024-11-12 23:46 ` [PATCH v2 bpf-next 0/4] Make inode storage available to tracing prog Martin KaFai Lau
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