Hello Martin,
On Thu, Nov 26, 2015 at 08:01:34PM +0100, martin.wi...@ts.fujitsu.com wrote:
> From: Martin Wilck <martin.wi...@ts.fujitsu.com>
>
> Since b8b2c7d845d5, platform_drv_probe() is called for all platform
> devices. If drv->probe is NULL, and dev_pm_domain_attach() fails,
> platform_drv_probe() will return the error code from dev_pm_domain_attach().
Correct, this is an unintended change of behaviour introduced in
b8b2c7d845d5.
> This causes real_probe() to enter the "probe_failed" path and set
> dev->driver to NULL. Before b8b2c7d845d5, real_probe() would assume
> success if both dev->bus->probe and drv->probe are missing.
>
> This may cause a panic later. For example, inserting the tpm_tis
> driver with parameter "force=1" (i.e. registering tpm_tis as a platform
> driver) will panic in tpmm_chip_alloc() because dev->driver is NULL:
>
> chip->cdev.owner = chip->pdev->driver->owner;
This sounds like a separate issue though. Looking at init_tis there is:
rc = platform_driver_register(&tis_drv);
if (rc < 0)
return rc;
pdev = platform_device_register_simple("tpm_tis", -1, NULL, 0);
if (IS_ERR(pdev)) {
rc = PTR_ERR(pdev);
goto err_dev;
}
rc = tpm_tis_init(&pdev->dev, &tis_default_info, NULL);
tpm_tis_init calls tpmm_chip_alloc which barfs when pdev (i.e. the return value
of platform_device_register_simple above) isn't bound. It is not allowed
to assume that the device is bound after the above function calls.
So I'd say drop the paragraph about tpm_tis and the change is fine.
> This patch fixes this by returning success in platform_drv_probe() if
> "just" dev_pm_domain_attach() had failed. This restores the semantics
> of platform_device_register_XXX() if the associated platform driver has
> no "probe" function.
>
> Fixes: b8b2c7d845d5 ("base/platform: assert that dev_pm_domain
> callbacks are called unconditionally")
>
I think line breaks in the Fixes: line are frowned on. Also usually
there is no empty line between Fixes: and S-o-b:.
> Signed-off-by: Martin Wilck <martin.wi...@ts.fujitsu.com>
> ---
> drivers/base/platform.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index 1dd6d3b..c994e76 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -513,10 +513,14 @@ static int platform_drv_probe(struct device *_dev)
> return ret;
>
> ret = dev_pm_domain_attach(_dev, true);
> - if (ret != -EPROBE_DEFER && drv->probe) {
> - ret = drv->probe(dev);
> - if (ret)
> - dev_pm_domain_detach(_dev, true);
> + if (ret != -EPROBE_DEFER) {
> + if (drv->probe) {
> + ret = drv->probe(dev);
> + if (ret)
> + dev_pm_domain_detach(_dev, true);
> + } else
> + /* don't fail if just dev_pm_domain_attach failed */
> + ret = 0;
An else that has a } should also have a {, according to
checkpatch and Documentation/CodingStyle. You can write it
alternatively as:
if (ret != -EPROBE_DEFER) {
if (drv->probe)
ret = drv->probe(dev);
else
ret = 0;
if (ret)
dev_pm_domain_detach(_dev, true);
}
.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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