From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 AE24C30E85B; Mon, 31 Aug 2026 03:02:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788145379; cv=none; b=NfZl0sn8syc2lxlI27ggoGga1WFc0JUThb0olqCyxMcni/hsTzns3hqvLRtUClttR2Sm2VoT25o4E/1vXgl9GA+E1uN5jssehTK9MVq3/6b3vM7ePtBQqSjvY5bXXsF+SdEGtzoo/Nlc5RRBZwDfIirTm5CNwWJVv4KcQKKlfR8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788145379; c=relaxed/simple; bh=7xAwu7GPkq66WqGt8IyauPsgkbs4KnZkfyNfebfC9nI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=c0tOolYRHhdjjHINQUGyLE15pHCDeUfJnyiF7W5o9KcwdDa0A/Q6k0Ut0DOhH/gmg67QN1NgcH9Kwvzsq9QE1WFRq6X+MWPJPNF7Ka06qGRiW5fEYtjyl6m0rEt4JR4LFS1Tbq9komACbOkM2NMPUZW/2LSzan9SQGS2gBs3Fmk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EMx2BUw/; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EMx2BUw/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 061B31F000E9; Mon, 31 Aug 2026 03:02:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788145378; bh=ETs+4Tl68muzBumLt5I6HKBvhH1PKmH1PnMlTtXNCJI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=EMx2BUw/mk9z5LR2kM5oqWedT160RYUpYEAIINZtWONcWcjqPg7BbXE56Qy6PEFam er/CkcI7E6VOBemyixM11nwUvcQ1XKBMiAncHZP91YpvllIrSPf8H/cLAQ/lpp332A Qtv+93+m9pamvx79iyt3kcinjJoV6MKxvr/VP/QOi3kTzsHgyO8811a6f7qByR/fyG knhMjDWoSOMdbwmEIkwrIlJXT6qKJJW/UOrunSUKjSy1TeTUI/iVnJy+lLsWabJA8k 4LxhuCGGnn23LXaza2y8FWpdBKPmMJzpXXJQ92qg6AOGPRlXY5F6M+6B332VUPtaom 2qZ+OGzzcdjTw== Message-ID: <602bdc5f-e9fa-4ed5-a009-03af860d31a6@kernel.org> Date: Mon, 31 Aug 2026 05:02:54 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/3] serial: core: replace get_zeroed_page() with kzalloc() To: "Mike Rapoport (Microsoft)" , Greg Kroah-Hartman Cc: Andrew Morton , David Hildenbrand , Matthew Wilcox , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-serial@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <20260830-tty-v1-0-0cbe6170649b@kernel.org> <20260830-tty-v1-2-0cbe6170649b@kernel.org> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 30. 08. 26, 9:49, Mike Rapoport (Microsoft) wrote: > uart_alloc_xmit_buf() allocates the transmit buffer of a serial port. The > buffer only backs the port's kfifo, the data being sent is copied in and > out of it. > > This buffer can be allocated with kmalloc() as there's nothing special > about it to go directly to the page allocator. > > kmalloc() provides a better API that does not require ugly casts and > kfree() does not need to know the size of the freed object. > > Performance difference between kmalloc() and __get_free_pages() is not > measurable as both allocators take an object/page from a per-CPU list for > fast path allocations. > > For the slow path the performance is anyway determined by the amount of > reclaim involved rather than by what allocator is used. > > While on it, make the local variable holding the buffer a pointer to get > rid of the casts. > > Replace use of get_zeroed_page() with kzalloc() and free_page() with > kfree(). > > Link: https://lore.kernel.org/all/635405e4-9423-4a25-a6e7-e03c8ea0bcbe@redhat.com > Assisted-by: copilot:claude-opus > Signed-off-by: Mike Rapoport (Microsoft) > --- > drivers/tty/serial/serial_core.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c > index 95774b0f1484..f12ce7d190fe 100644 > --- a/drivers/tty/serial/serial_core.c > +++ b/drivers/tty/serial/serial_core.c > @@ -247,29 +247,29 @@ static int uart_alloc_xmit_buf(struct tty_port *port) > struct uart_state *state = container_of(port, struct uart_state, port); > struct uart_port *uport; > unsigned long flags; > - unsigned long page; 1: > + unsigned char *buf; > > /* > * Initialise and allocate the transmit and temporary > * buffer. > */ > - page = get_zeroed_page(GFP_KERNEL); > - if (!page) > + buf = kzalloc(PAGE_SIZE, GFP_KERNEL); > + if (!buf) > return -ENOMEM; > > uport = uart_port_ref_lock(state, &flags); > if (!state->port.xmit_buf) { > - state->port.xmit_buf = (unsigned char *)page; > + state->port.xmit_buf = buf; xmit_buf is u8 *. This uchar was omitted when I was changing the type back then. Could you use the right type at 1b now? thanks, -- js suse labs