spi: fix bogus SPI bus number

Message ID 20171017104519.878892-1-arnd@arndb.de
State New
Headers show
Series
  • spi: fix bogus SPI bus number
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Commit Message

Arnd Bergmann Oct. 17, 2017, 10:44 a.m.
lkft found a boot time regression on the Hikey board that has no
aliases entry for spi buses. of_alias_get_highest_id() here
returns -ENODEV, which is then used as the initial number for the
IDR allocation, and that in turn triggers a WARN_ON:

WARNING: CPU: 3 PID: 53 at include/linux/idr.h:113 spi_register_controller+0x890/0x940

This reworks the algorithm to turn any negative number into zero
again, restoring the original behavior for the Hikey case.

Fixes: 9ce70d49fa80 ("spi: fix IDR collision on systems with both fixed and dynamic SPI bus numbers")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Link: https://lkft.validation.linaro.org/scheduler/job/48009#L3147
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
Not tested yet, please review carefully
---
 drivers/spi/spi.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

-- 
2.9.0

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Comments

Lucas Stach Oct. 17, 2017, 12:20 p.m. | #1
Am Dienstag, den 17.10.2017, 12:44 +0200 schrieb Arnd Bergmann:
> lkft found a boot time regression on the Hikey board that has no

> aliases entry for spi buses. of_alias_get_highest_id() here

> returns -ENODEV, which is then used as the initial number for the

> IDR allocation, and that in turn triggers a WARN_ON:

> 

> WARNING: CPU: 3 PID: 53 at include/linux/idr.h:113

> spi_register_controller+0x890/0x940

> 

> This reworks the algorithm to turn any negative number into zero

> again, restoring the original behavior for the Hikey case.

> 

> Fixes: 9ce70d49fa80 ("spi: fix IDR collision on systems with both

> fixed and dynamic SPI bus numbers")

> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>

> Link: https://lkft.validation.linaro.org/scheduler/job/48009#L3147

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

> ---

> Not tested yet, please review carefully


I've already sent a v2 of the borked patch, which Mark apparently
applied to his fix/idr branch.

Regards,
Lucas

> ---

>  drivers/spi/spi.c | 6 ++++--

>  1 file changed, 4 insertions(+), 2 deletions(-)

> 

> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c

> index 0483410e7cb3..4b6985ec962c 100644

> --- a/drivers/spi/spi.c

> +++ b/drivers/spi/spi.c

> @@ -2116,9 +2116,11 @@ int spi_register_controller(struct

> spi_controller *ctlr)

>  	}

>  	if (ctlr->bus_num < 0) {

>  		mutex_lock(&board_lock);

> +		id = of_alias_get_highest_id("spi");

> +		if (id < 0)

> +			id = -1;

>  		id = idr_alloc(&spi_master_idr, ctlr,

> -			       of_alias_get_highest_id("spi") + 1,

> -			       0, GFP_KERNEL);

> +			       id + 1, 0, GFP_KERNEL);

>  		mutex_unlock(&board_lock);

>  		if (WARN(id < 0, "couldn't get idr"))

>  			return id;

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Mark Brown Oct. 17, 2017, 12:25 p.m. | #2
On Tue, Oct 17, 2017 at 12:44:50PM +0200, Arnd Bergmann wrote:
> lkft found a boot time regression on the Hikey board that has no

> aliases entry for spi buses. of_alias_get_highest_id() here

> returns -ENODEV, which is then used as the initial number for the

> IDR allocation, and that in turn triggers a WARN_ON:


This doesn't apply against current code, please check and resend.

Patch

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 0483410e7cb3..4b6985ec962c 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2116,9 +2116,11 @@  int spi_register_controller(struct spi_controller *ctlr)
 	}
 	if (ctlr->bus_num < 0) {
 		mutex_lock(&board_lock);
+		id = of_alias_get_highest_id("spi");
+		if (id < 0)
+			id = -1;
 		id = idr_alloc(&spi_master_idr, ctlr,
-			       of_alias_get_highest_id("spi") + 1,
-			       0, GFP_KERNEL);
+			       id + 1, 0, GFP_KERNEL);
 		mutex_unlock(&board_lock);
 		if (WARN(id < 0, "couldn't get idr"))
 			return id;