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().
>
> 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 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")
>
> Signed-off-by: Martin Wilck <martin.wi...@ts.fujitsu.com>
Acked-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.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;
> }
>
> if (drv->prevent_deferred_probe && ret == -EPROBE_DEFER) {
> --
> 1.8.3.1
>
>
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