From: Kirill Kapranov <kirill.kapranov@compulab.co.il>
To: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Mark Brown <broonie@kernel.org>,
linux-spi@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH -next] spi: Fix double IDR allocation with DT aliases
Date: Wed, 22 Aug 2018 20:51:40 +0300 [thread overview]
Message-ID: <35fbd3ae-3ac3-f6ef-874b-3d99c4d4d29a@compulab.co.il> (raw)
In-Reply-To: <20180821095303.27664-1-geert+renesas@glider.be>
Hi Geert
Thank you for keeping me informed.
I have to point at the following threat: a dynamically allocated ID may
'squat' a bus ID that intended for a device with statically allocated
ID. This scenario is possible since module loading order is uncertain.
This threat seems to be inevitable...
--
Best regards,
Kirill.
On 08/21/2018 12:53 PM, Geert Uytterhoeven wrote:
> If the SPI bus number is provided by a DT alias, idr_alloc() is called
> twice, leading to:
>
> WARNING: CPU: 1 PID: 1 at drivers/spi/spi.c:2179 spi_register_controller+0x11c/0x5d8
> couldn't get idr
>
> Fix this by moving the handling of fixed SPI bus numbers up, before the
> DT handling code fills in ctlr->bus_num.
>
> Fixes: 1a4327fbf4554d5b ("spi: fix IDR collision on systems with both fixed and dynamic SPI bus numbers")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> Seen on e.g. r8a7791/koelsch, breaking both RSPI and MSIOF.
> ---
> drivers/spi/spi.c | 22 +++++++++++-----------
> 1 file changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index a00d006d4c3a1c5a..9da0bc5a036cfff6 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -2143,8 +2143,17 @@ int spi_register_controller(struct spi_controller *ctlr)
> */
> if (ctlr->num_chipselect == 0)
> return -EINVAL;
> - /* allocate dynamic bus number using Linux idr */
> - if ((ctlr->bus_num < 0) && ctlr->dev.of_node) {
> + if (ctlr->bus_num >= 0) {
> + /* devices with a fixed bus num must check-in with the num */
> + mutex_lock(&board_lock);
> + id = idr_alloc(&spi_master_idr, ctlr, ctlr->bus_num,
> + ctlr->bus_num + 1, GFP_KERNEL);
> + mutex_unlock(&board_lock);
> + if (WARN(id < 0, "couldn't get idr"))
> + return id == -ENOSPC ? -EBUSY : id;
> + ctlr->bus_num = id;
> + } else if (ctlr->dev.of_node) {
> + /* allocate dynamic bus number using Linux idr */
> id = of_alias_get_id(ctlr->dev.of_node, "spi");
> if (id >= 0) {
> ctlr->bus_num = id;
> @@ -2170,15 +2179,6 @@ int spi_register_controller(struct spi_controller *ctlr)
> if (WARN(id < 0, "couldn't get idr"))
> return id;
> ctlr->bus_num = id;
> - } else {
> - /* devices with a fixed bus num must check-in with the num */
> - mutex_lock(&board_lock);
> - id = idr_alloc(&spi_master_idr, ctlr, ctlr->bus_num,
> - ctlr->bus_num + 1, GFP_KERNEL);
> - mutex_unlock(&board_lock);
> - if (WARN(id < 0, "couldn't get idr"))
> - return id == -ENOSPC ? -EBUSY : id;
> - ctlr->bus_num = id;
> }
> INIT_LIST_HEAD(&ctlr->queue);
> spin_lock_init(&ctlr->queue_lock);
>
next prev parent reply other threads:[~2018-08-22 17:51 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-21 9:53 [PATCH -next] spi: Fix double IDR allocation with DT aliases Geert Uytterhoeven
2018-08-21 13:40 ` Greg KH
2018-08-21 17:42 ` Geert Uytterhoeven
2018-08-22 17:51 ` Kirill Kapranov [this message]
2018-08-23 10:21 ` Mark Brown
2018-08-25 17:54 ` Kirill Kapranov
2018-08-26 13:24 ` Mark Brown
2018-08-28 19:47 ` Kirill kapranov
2018-08-27 14:13 ` Fabio Estevam
2018-08-28 20:58 ` Applied "spi: Fix double IDR allocation with DT aliases" to the spi tree Mark Brown
2018-08-28 20:58 ` Mark Brown
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=35fbd3ae-3ac3-f6ef-874b-3d99c4d4d29a@compulab.co.il \
--to=kirill.kapranov@compulab.co.il \
--cc=broonie@kernel.org \
--cc=geert+renesas@glider.be \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-renesas-soc@vger.kernel.org \
--cc=linux-spi@vger.kernel.org \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.