Hi Paul,
Le 08/06/2019 à 11:57, Paul Cercueil a écrit :
Hi Christophe,
Le sam. 8 juin 2019 à 9:51, Christophe Leroy <christophe.leroy@xxxxxx> a
écrit :
Hi Paul,
Le 07/06/2019 à 18:24, Paul Cercueil a écrit :
This allows the probe function to be dropped after the kernel finished
its initialization, in the case where the driver was not compiled as a
module.
I'm not sure that's what __init_or_module flag does.
As far as I understand, this flag makes the function being dropped
only when the kernel is built without modules support, ie without
CONFIG_MODULES. See
https://elixir.bootlin.com/linux/latest/source/include/linux/module.h#L145
So it doesn't depend on the driver being built-in or compiled as a module?
No it doesn't. This flag is for built-in functions that are needed by
init and modules init. If the kernel doesn't support modules, it can
drop the function after init. If the kernel supports modules, it has to
keep the function. That's what this flag is made for.
If your need is to mark a function so that it gets discarded after init
or module init, just mark it __init. If it is built in, it will be
dropped after init. If it is in a module, it will be dropped after the
module is initialised.
In addition, I'm not sure you can simply define a probe function as
__init. What if someone tries to unbind and rebind the device through
sysfs for instance ?
Ouch. I feel stupid now.
It seems there is a special function called __platform_driver_probe()
for registering devices when the probe function is to be in __init,
see
https://elixir.bootlin.com/linux/latest/source/drivers/base/platform.c#L684
Yes, but only usable by drivers that won't defer probe, and it removes
the bind/unbind attributes from sysfs,
so it shouldn't be used for non-critical drivers, I think.
I guess it would make sense for watchdog drivers, we don't expect this
kind of driver to be unbinded, do we ?
Christophe
Christophe
Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
---
Notes:
v2: New patch
drivers/watchdog/jz4740_wdt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/watchdog/jz4740_wdt.c
b/drivers/watchdog/jz4740_wdt.c
index 7519d80c5d05..2061788c1939 100644
--- a/drivers/watchdog/jz4740_wdt.c
+++ b/drivers/watchdog/jz4740_wdt.c
@@ -157,7 +157,7 @@ static const struct of_device_id
jz4740_wdt_of_matches[] = {
MODULE_DEVICE_TABLE(of, jz4740_wdt_of_matches);
#endif
-static int jz4740_wdt_probe(struct platform_device *pdev)
+static int __init_or_module jz4740_wdt_probe(struct platform_device
*pdev)
{
struct device *dev = &pdev->dev;
struct jz4740_wdt_drvdata *drvdata;
