[PATCH] spi: fix IDR collision on systems with both fixed and dynamic SPI bus numbers

[PATCH] spi: fix IDR collision on systems with both fixed and dynamic SPI bus numbers

[Lucas Stach]

On systems where some controllers get a dynamic ID assigned and some have
a fixed number from DT, the current implemention might run into an IDR
collision if the dynamic controllers gets probed first and get an IDR number,
which is later requested by the controller with the fixed numbering. When
this happens the fixed controller will fail to register with the SPI core.

Fix this by skipping all known alias numbers when assigning the dynamic IDs.

Fixes: 9b61e302210e (spi: Pick spi bus number from Linux idr or spi alias)
Signed-off-by: Lucas Stach <l.stach-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
---
 drivers/spi/spi.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 6e65524cbfd9..0483410e7cb3 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -45,7 +45,6 @@
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/spi.h>
-#define SPI_DYN_FIRST_BUS_NUM 0
 
 static DEFINE_IDR(spi_master_idr);
 
@@ -2117,8 +2116,9 @@ int spi_register_controller(struct spi_controller *ctlr)
 	}
 	if (ctlr->bus_num < 0) {
 		mutex_lock(&board_lock);
-		id = idr_alloc(&spi_master_idr, ctlr, SPI_DYN_FIRST_BUS_NUM, 0,
-			       GFP_KERNEL);
+		id = idr_alloc(&spi_master_idr, ctlr,
+			       of_alias_get_highest_id("spi") + 1,
+			       0, GFP_KERNEL);
 		mutex_unlock(&board_lock);
 		if (WARN(id < 0, "couldn't get idr"))
 			return id;
-- 
2.11.0

--
To unsubscribe from this list: send the line "unsubscribe linux-spi" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH] spi: fix IDR collision on systems with both fixed and dynamic SPI bus numbers

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 782 bytes --]

On Fri, Oct 13, 2017 at 05:59:46PM +0200, Lucas Stach wrote:

> Fix this by skipping all known alias numbers when assigning the dynamic IDs.

> -		id = idr_alloc(&spi_master_idr, ctlr, SPI_DYN_FIRST_BUS_NUM, 0,
> -			       GFP_KERNEL);
> +		id = idr_alloc(&spi_master_idr, ctlr,
> +			       of_alias_get_highest_id("spi") + 1,
> +			       0, GFP_KERNEL);

I'll apply this but I'm wondering if we want to have the static bus
number allocation also allocate that number out of the IDR so the IDR
code handles things more transparently.  Feels like it's more trouble
than it's worth though, this should work fine.  I'm also worrying about
the case where IDR allocated a number before a static assignment got to
it...  not much we can do to guarantee that we avoid that case though.

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Applied "spi: fix IDR collision on systems with both fixed and dynamic SPI bus numbers" to the spi tree

[Mark Brown]

The patch

   spi: fix IDR collision on systems with both fixed and dynamic SPI bus numbers

has been applied to the spi tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 9ce70d49fa80b95a029c16432270f4edbbd2a953 Mon Sep 17 00:00:00 2001
From: Lucas Stach <l.stach-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Date: Fri, 13 Oct 2017 17:59:46 +0200
Subject: [PATCH] spi: fix IDR collision on systems with both fixed and dynamic
 SPI bus numbers

On systems where some controllers get a dynamic ID assigned and some have
a fixed number from DT, the current implemention might run into an IDR
collision if the dynamic controllers gets probed first and get an IDR number,
which is later requested by the controller with the fixed numbering. When
this happens the fixed controller will fail to register with the SPI core.

Fix this by skipping all known alias numbers when assigning the dynamic IDs.

Fixes: 9b61e302210e (spi: Pick spi bus number from Linux idr or spi alias)
Signed-off-by: Lucas Stach <l.stach-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Signed-off-by: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 drivers/spi/spi.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 6e65524cbfd9..0483410e7cb3 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -45,7 +45,6 @@
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/spi.h>
-#define SPI_DYN_FIRST_BUS_NUM 0
 
 static DEFINE_IDR(spi_master_idr);
 
@@ -2117,8 +2116,9 @@ int spi_register_controller(struct spi_controller *ctlr)
 	}
 	if (ctlr->bus_num < 0) {
 		mutex_lock(&board_lock);
-		id = idr_alloc(&spi_master_idr, ctlr, SPI_DYN_FIRST_BUS_NUM, 0,
-			       GFP_KERNEL);
+		id = idr_alloc(&spi_master_idr, ctlr,
+			       of_alias_get_highest_id("spi") + 1,
+			       0, GFP_KERNEL);
 		mutex_unlock(&board_lock);
 		if (WARN(id < 0, "couldn't get idr"))
 			return id;
-- 
2.14.1

--
To unsubscribe from this list: send the line "unsubscribe linux-spi" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH] spi:fix IDR collision on systems with both fixed and dynamic SPI bus numbers

[Kirill Kapranov]

On systems where some controllers get a dynamic ID assigned and some have
a fixed number (e.g. from ACPI tables), the current implementation might
run into an IDR collision: in case of a fixed bus number is gotten by a
driver (but not marked busy in IDR tree) and a driver with dynamic bus
number gets the same ID and predictably fails.

Fix this by means of checking-in fixed IDsin IDR as far as dynamic ones
at the moment of the controller registration.

Fixes: 9b61e302210e (spi: Pick spi bus number from Linux idr or spi alias)

Signed-off-by: Kirill Kapranov <kirill.kapranov@compulab.co.il>
---
 drivers/spi/spi.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index ec395a6baf9c..97e303185d5b 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2170,6 +2170,15 @@ 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);
-- 
2.11.0

Re: [PATCH] spi:fix IDR collision on systems with both fixed and dynamic SPI bus numbers

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 667 bytes --]

On Mon, Aug 13, 2018 at 07:48:10PM +0300, Kirill Kapranov wrote:
> On systems where some controllers get a dynamic ID assigned and some have
> a fixed number (e.g. from ACPI tables), the current implementation might
> run into an IDR collision: in case of a fixed bus number is gotten by a
> driver (but not marked busy in IDR tree) and a driver with dynamic bus
> number gets the same ID and predictably fails.

Is this something that's actually happened for you?

> +	} else {
> +	/* devices with a fixed bus num must check-in with the num */
> +		mutex_lock(&board_lock);

The indentation here is weird, the comment isn't aligned with the code
it's commenting on.

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]