[PATCH] i2c: i801: Annotate apanel_addr as __ro_after_init

[PATCH] i2c: i801: Annotate apanel_addr as __ro_after_init

[Heiner Kallweit]

Annotate this variable as __ro_after_init to protect it from being
overwritten later.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/i2c/busses/i2c-i801.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 6d027a77d..e577abc77 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -1060,7 +1060,7 @@ static const struct pci_device_id i801_ids[] = {
 MODULE_DEVICE_TABLE(pci, i801_ids);
 
 #if defined CONFIG_X86 && defined CONFIG_DMI
-static unsigned char apanel_addr;
+static unsigned char apanel_addr __ro_after_init;
 
 /* Scan the system ROM for the signature "FJKEYINF" */
 static __init const void __iomem *bios_signature(const void __iomem *bios)
-- 
2.44.0

Re: [PATCH] i2c: i801: Annotate apanel_addr as __ro_after_init

[Wolfram Sang]

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>  #if defined CONFIG_X86 && defined CONFIG_DMI

Shouldn't that be on top of "[PATCH v2] i2c: i801: Fix missing Kconfig
dependency" which Andi already merged?


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Re: [PATCH] i2c: i801: Annotate apanel_addr as __ro_after_init

[Heiner Kallweit]

On 12.04.2024 12:30, Wolfram Sang wrote:
>>  #if defined CONFIG_X86 && defined CONFIG_DMI
> 
> Shouldn't that be on top of "[PATCH v2] i2c: i801: Fix missing Kconfig
> dependency" which Andi already merged?
> 
No, this is a different code part here. The other one was
protected with:
#if IS_ENABLED(CONFIG_I2C_MUX_GPIO) && defined CONFIG_DMI

Re: [PATCH] i2c: i801: Annotate apanel_addr as __ro_after_init

[Wolfram Sang]

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> No, this is a different code part here. The other one was

Oh. Sorry for the noise!


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Re: [PATCH] i2c: i801: Annotate apanel_addr as __ro_after_init

[Andi Shyti]

Hi Heiner,

On Fri, Apr 12, 2024 at 12:21:58PM +0200, Heiner Kallweit wrote:
> Annotate this variable as __ro_after_init to protect it from being
> overwritten later.

What is the reason behind this patch? Where is the risk of
overwriting this variable?

Andi

Re: [PATCH] i2c: i801: Annotate apanel_addr as __ro_after_init

[Heiner Kallweit]

On 15.04.2024 23:05, Andi Shyti wrote:
> Hi Heiner,
> 
> On Fri, Apr 12, 2024 at 12:21:58PM +0200, Heiner Kallweit wrote:
>> Annotate this variable as __ro_after_init to protect it from being
>> overwritten later.
> 
> What is the reason behind this patch? Where is the risk of
> overwriting this variable?
> 
The annotation makes clear that this variable is to be written
by init code only, w/o having to check all usage in the driver.
Currently the variable isn't written later, however the annotation
protects from any such potential attempt in the future.
The original commit message has more arguments for using this
annotation. https://lwn.net/Articles/676145/

> Andi

Heiner

Re: [PATCH] i2c: i801: Annotate apanel_addr as __ro_after_init

[Andi Shyti]

Hi

On Fri, 12 Apr 2024 12:21:58 +0200, Heiner Kallweit wrote:
> Annotate this variable as __ro_after_init to protect it from being
> overwritten later.
> 
> 

Applied to i2c/i2c-host on

git://git.kernel.org/pub/scm/linux/kernel/git/andi.shyti/linux.git

Thank you,
Andi

Patches applied
===============
[1/1] i2c: i801: Annotate apanel_addr as __ro_after_init
      commit: 08944c074592041873f1cb3e5be5fc3fd4cdc3ad