linux-kernel - Re: [PATCH 4/7] io_uring/bpf_filter: cache lookup table in ctx->bpf

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Message-ID: <20260127-akrobatisch-couch-5bba9980d78e@brauner>
Date: Tue, 27 Jan 2026 10:33:46 +0100
From: Christian Brauner <brauner@...nel.org>
To: Jens Axboe <axboe@...nel.dk>
Cc: io-uring@...r.kernel.org, jannh@...gle.com, kees@...nel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/7] io_uring/bpf_filter: cache lookup table in
 ctx->bpf_filters

On Mon, Jan 19, 2026 at 04:54:27PM -0700, Jens Axboe wrote:
> Currently a few pointer dereferences need to be made to both check if
> BPF filters are installed, and then also to retrieve the actual filter
> for the opcode. Cache the table in ctx->bpf_filters to avoid that.
> 
> Add a bit of debug info on ring exit to show if we ever got this wrong.
> Small risk of that given that the table is currently only updated in one
> spot, but once task forking is enabled, that will add one more spot.
> 
> Signed-off-by: Jens Axboe <axboe@...nel.dk>
> ---

Reviewed-by: Christian Brauner <brauner@...nel.org>