From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 213583C2F; Thu, 18 Dec 2025 01:48:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766022498; cv=none; b=bD76rztQ3ky9NEJzyUMdTVLbLcfsFvGIF2b9wpYn4Os0qjGWbAjljPYVR39kjq6JXfrdCEu1HpwhPixcxuAmEmv04h8qc5aViPHoX199Wqdx+sm5buYHyp0t6FY0i/MxkYirkrQ7TcxwxNUC8jVw24RQo/spcdvTUUSNGrT1zxg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766022498; c=relaxed/simple; bh=dQlBuB3KnyMoKeAYJ0vjAIrQK6ORdk+MFt6eBG/8Btg=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=EtKpIJVk4q1abyTySAscRuKqnCnLIsglTQ6O0ViasfBlM+EMJkp5x5THCmv056OsrHUthr18mrngqZ6KslMANYKoZ8+iuSeG7htUsBFAkXEHL1rYwa47O7U1/QheAKC8Z01VDfG1wm6FOfydLO4V2JerE63OdY3te6HYSmURar8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SdxJLF3C; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="SdxJLF3C" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 324F6C4CEF5; Thu, 18 Dec 2025 01:48:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766022497; bh=dQlBuB3KnyMoKeAYJ0vjAIrQK6ORdk+MFt6eBG/8Btg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=SdxJLF3CukKnvJa2ypw7qV5usHJoBdKs7WGFk2LjAAUOVNYhDyZdXuftwp3XBJKDA 8F8zhdWarRMtr2qax8/EoTFH8U2t/Otkqesr9ld9RChHJZc6CbiJQm2/uOE2DHpDRj AH8t+IswcNb98bAmui+BVD9WD5LeyeYkI4zpLP5tN/90wTXUvFRVLpn/w8Faffs+bv toLDtCCwuTb9r9I/Pq9ZIemp5VBWw3N/reR1+rG+2YsoIaXG33sPUf9TpIToS9cgph J8ALVsLj1LBDtOiDXpcjSxCZ4ibTyylPLmrBzBrFfftd+Pk/2575dO7JTNUMB5Qrp1 MElyM7Jle3vLg== Date: Wed, 17 Dec 2025 20:48:14 -0500 From: Steven Rostedt To: Jiri Olsa Cc: Florent Revest , Mark Rutland , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Menglong Dong , Song Liu Subject: Re: [PATCHv5 bpf-next 5/9] ftrace: Add update_ftrace_direct_del function Message-ID: <20251217204814.38756224@robin> In-Reply-To: <20251215211402.353056-6-jolsa@kernel.org> References: <20251215211402.353056-1-jolsa@kernel.org> <20251215211402.353056-6-jolsa@kernel.org> X-Mailer: Claws Mail 4.3.1 (GTK 3.24.51; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 15 Dec 2025 22:13:58 +0100 Jiri Olsa wrote: > +/** > + * hash_sub - substracts @b from @a and returns the result > + * @a: struct ftrace_hash object > + * @b: struct ftrace_hash object > + * > + * Returns struct ftrace_hash object on success, NULL on error. > + */ > +static struct ftrace_hash *hash_sub(struct ftrace_hash *a, struct ftrace_hash *b) > +{ > + struct ftrace_func_entry *entry, *del; > + struct ftrace_hash *sub; > + int size, i; > + > + sub = alloc_and_copy_ftrace_hash(a->size_bits, a); > + if (!sub) > + goto error; Again, this can be just return NULL; > + > + size = 1 << b->size_bits; > + for (i = 0; i < size; i++) { You can make this for (int i = 0; ...) too. > + hlist_for_each_entry(entry, &b->buckets[i], hlist) { > + del = __ftrace_lookup_ip(sub, entry->ip); > + if (WARN_ON_ONCE(!del)) > + goto error; And you can remove the error label here too: if (WARN_ON_ONCE(!del)) { free_ftrace_hash(sub); return NULL; } > + remove_hash_entry(sub, del); > + kfree(del); > + } > + } > + return sub; > + > + error: > + free_ftrace_hash(sub); > + return NULL; > +} > + > +int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash) > +{ > + struct ftrace_hash *old_direct_functions = NULL, *new_direct_functions; > + struct ftrace_hash *old_filter_hash, *new_filter_hash = NULL; > + struct ftrace_func_entry *del, *entry; One variable per line. > + unsigned long size, i; > + int err = -EINVAL; > + > + if (!hash_count(hash)) > + return -EINVAL; > + if (check_direct_multi(ops)) > + return -EINVAL; > + if (!(ops->flags & FTRACE_OPS_FL_ENABLED)) > + return -EINVAL; > + if (direct_functions == EMPTY_HASH) > + return -EINVAL; > + > + mutex_lock(&direct_mutex); > + > + old_filter_hash = ops->func_hash ? ops->func_hash->filter_hash : NULL; > + > + if (!hash_count(old_filter_hash)) > + goto out_unlock; > + > + /* Make sure requested entries are already registered. */ > + size = 1 << hash->size_bits; > + for (i = 0; i < size; i++) { for (int i = 0; ...) -- Steve > + hlist_for_each_entry(entry, &hash->buckets[i], hlist) { > + del = __ftrace_lookup_ip(direct_functions, entry->ip); > + if (!del || del->direct != entry->direct) > + goto out_unlock; > + } > + } > + > + err = -ENOMEM; > + new_filter_hash = hash_sub(old_filter_hash, hash); > + if (!new_filter_hash) > + goto out_unlock; > + > + new_direct_functions = hash_sub(direct_functions, hash); > + if (!new_direct_functions) > + goto out_unlock; > + > + /* If there's nothing left, we need to unregister the ops. */ > + if (ftrace_hash_empty(new_filter_hash)) { > + err = unregister_ftrace_function(ops); > + if (!err) { > + /* cleanup for possible another register call */ > + ops->func = NULL; > + ops->trampoline = 0; > + ftrace_free_filter(ops); > + ops->func_hash->filter_hash = NULL; > + } > + } else { > + err = ftrace_update_ops(ops, new_filter_hash, EMPTY_HASH); > + /* > + * new_filter_hash is dup-ed, so we need to release it anyway, > + * old_filter_hash either stays on error or is already released > + */ > + } > + > + if (err) { > + /* free the new_direct_functions */ > + old_direct_functions = new_direct_functions; > + } else { > + rcu_assign_pointer(direct_functions, new_direct_functions); > + } > + > + out_unlock: > + mutex_unlock(&direct_mutex); > + > + if (old_direct_functions && old_direct_functions != EMPTY_HASH) > + call_rcu_tasks(&old_direct_functions->rcu, register_ftrace_direct_cb); > + free_ftrace_hash(new_filter_hash); > + > + return err; > +} > + > #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ > > /**