Re: [tpmdd-devel] [PATCH] tpm: fix rollback/cleanup before tpm_chip_register()
From: Jason Gunthorpe <hidden>
Date: 2016-02-02 23:14:03
Also in:
lkml
On Sat, Jan 30, 2016 at 06:05:42PM -0800, Jarkko Sakkinen wrote:
The release-callback is not used before the device is attached to the device hierarchy. This caused resources not to cleanup properly if the device driver initialization failed before tpm_chip_register().
This commentary is not right, the release callback is callable immediately after device_initialize returns, it will be called by the last put_device().
- * tpmm_chip_alloc() - allocate a new struct tpm_chip instance - * @dev: device to which the chip is associated + * tpmm_chip_alloc() - allocate and initialize a TPM chip + * @pdev: the platform device who is the parent of the chip
? A platform device is not required, just something in a state that can handle devm.
+ /* Associate character device with the platform device only after + * it is properly initialized. + */ + dev_set_drvdata(pdev, chip); + devm_add_action(pdev, (void (*)(void *)) tpm_dev_release, &chip->dev);
No, a release function can never be called naked. The action needs to do put_device, which is the error unwind for device_initialize().
quoted hunk ↗ jump to hunk
@@ -162,7 +165,10 @@ static int tpm_add_char_device(struct tpm_chip *chip) MINOR(chip->dev.devt), rc); cdev_del(&chip->cdev); - return rc; + } else { + devm_remove_action(chip->dev.parent, + (void (*)(void *)) tpm_dev_release, + &chip->dev);
This is in the wrong place, the devm should be canceled only if tpm_chip_register returns success, at that point the caller's contract is to guarentee a call to tpm_chip_unregister, and tpm_chip_unregister does the put_device that calls the release function. Jason