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Date: Fri, 11 Mar 2016 21:50:59 -0500 From: Stefan Berger <stefanb@...ux.vnet.ibm.com> To: tpmdd-devel@...ts.sourceforge.net Cc: jarkko.sakkinen@...ux.intel.com, jgunthorpe@...idianresearch.com, linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org, Stefan Berger <stefanb@...ux.vnet.ibm.com> Subject: [PATCH v7 04/10] tpm: Get rid of module locking Now that the tpm core has strong locking around 'ops' it is possible to remove a TPM driver, module and all, even while user space still has things like /dev/tpmX open. For consistency and simplicity, drop the module locking entirely. The module lock can be dropped since /dev/tpmX holds the reader lock on 'ops' while using 'ops' and this prevents the module from un- registering, which needs the writer lock. Once the module unregistered the 'ops' cannot be found anymore. Signed-off-by: Stefan Berger <stefanb@...ux.vnet.ibm.com> Reviewed-by: Jason Gunthorpe <jgunthorpe@...idianresearch.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com> --- drivers/char/tpm/tpm-chip.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index 5793ea1..6636728 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -57,9 +57,6 @@ int tpm_try_get_ops(struct tpm_chip *chip) if (!chip->ops) goto out_lock; - if (!try_module_get(chip->dev.parent->driver->owner)) - goto out_lock; - return 0; out_lock: up_read(&chip->ops_sem); @@ -77,7 +74,6 @@ EXPORT_SYMBOL_GPL(tpm_try_get_ops); */ void tpm_put_ops(struct tpm_chip *chip) { - module_put(chip->dev.parent->driver->owner); up_read(&chip->ops_sem); put_device(&chip->dev); } @@ -183,7 +179,7 @@ struct tpm_chip *tpmm_chip_alloc(struct device *dev, goto out; cdev_init(&chip->cdev, &tpm_fops); - chip->cdev.owner = dev->driver->owner; + chip->cdev.owner = THIS_MODULE; chip->cdev.kobj.parent = &chip->dev.kobj; rc = devm_add_action(dev, (void (*)(void *)) put_device, &chip->dev); -- 2.4.3
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