Commit 700d8bdc authored by Nishanth Aravamudan's avatar Nishanth Aravamudan Committed by Linus Torvalds
Browse files

[PATCH] char/tpm: use msleep(), clean-up timers, 



The TPM driver unnecessarily uses timers when it simply needs to maintain a
maximum delay via time_before().  msleep() is used instead of
schedule_timeout() to guarantee the task delays as expected.  While
compile-testing, I found a typo in the driver, using tpm_chp instead of
tpm_chip.  Remove the now unused timer callback function and change
TPM_TIMEOUT's units to milliseconds.  Patch is compile-tested.

Signed-off-by: default avatarNishanth Aravamudan <nacc@us.ibm.com>
Acked-by: default avatarKylene Hall <kjhall@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 6a94f920

drivers/char/tpm/tpm.c

+7 −28
Original line number Diff line number Diff line
@@ -19,7 +19,7 @@ 
 * 

 * Note, the TPM chip is not interrupt driven (only polling)

 * and can have very long timeouts (minutes!). Hence the unusual

 * calls to schedule_timeout.

 * calls to msleep.

 *

 */
@@ -52,14 +52,6 @@ static void user_reader_timeout(unsigned long ptr) 
	up(&chip->buffer_mutex);

}



void tpm_time_expired(unsigned long ptr)

{

	int *exp = (int *) ptr;

	*exp = 1;

}



EXPORT_SYMBOL_GPL(tpm_time_expired);



/*

 * Initialize the LPC bus and enable the TPM ports

 */
@@ -135,6 +127,7 @@ static ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf, 
	ssize_t len;

	u32 count;

	__be32 *native_size;

	unsigned long stop;



	native_size = (__force __be32 *) (buf + 2);

	count = be32_to_cpu(*native_size);
@@ -155,28 +148,16 @@ static ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf, 
		return len;

	}



	down(&chip->timer_manipulation_mutex);

	chip->time_expired = 0;

	init_timer(&chip->device_timer);

	chip->device_timer.function = tpm_time_expired;

	chip->device_timer.expires = jiffies + 2 * 60 * HZ;

	chip->device_timer.data = (unsigned long) &chip->time_expired;

	add_timer(&chip->device_timer);

	up(&chip->timer_manipulation_mutex);



	stop = jiffies + 2 * 60 * HZ;

	do {

		u8 status = inb(chip->vendor->base + 1);

		if ((status & chip->vendor->req_complete_mask) ==

		    chip->vendor->req_complete_val) {

			down(&chip->timer_manipulation_mutex);

			del_singleshot_timer_sync(&chip->device_timer);

			up(&chip->timer_manipulation_mutex);

			goto out_recv;

		}

		set_current_state(TASK_UNINTERRUPTIBLE);

		schedule_timeout(TPM_TIMEOUT);

		msleep(TPM_TIMEOUT); /* CHECK */

		rmb();

	} while (!chip->time_expired);

	} while (time_before(jiffies, stop));





	chip->vendor->cancel(chip);
@@ -453,10 +434,8 @@ ssize_t tpm_write(struct file * file, const char __user * buf, 


	/* cannot perform a write until the read has cleared

	   either via tpm_read or a user_read_timer timeout */

	while (atomic_read(&chip->data_pending) != 0) {

		set_current_state(TASK_UNINTERRUPTIBLE);

		schedule_timeout(TPM_TIMEOUT);

	}

	while (atomic_read(&chip->data_pending) != 0)

		msleep(TPM_TIMEOUT);



	down(&chip->buffer_mutex);

drivers/char/tpm/tpm.h

+1 −2
Original line number Diff line number Diff line
@@ -25,7 +25,7 @@ 
#include <linux/fs.h>

#include <linux/miscdevice.h>



#define TPM_TIMEOUT msecs_to_jiffies(5)

#define TPM_TIMEOUT	5	/* msecs */



/* TPM addresses */

#define	TPM_ADDR			0x4E
@@ -78,7 +78,6 @@ static inline void tpm_write_index(int index, int value) 
	outb(value & 0xFF, TPM_DATA);

}



extern void tpm_time_expired(unsigned long);

extern int tpm_lpc_bus_init(struct pci_dev *, u16);



extern int tpm_register_hardware(struct pci_dev *,

drivers/char/tpm/tpm_nsc.c

+10 −22
Original line number Diff line number Diff line
@@ -55,10 +55,7 @@ 
 */

static int wait_for_stat(struct tpm_chip *chip, u8 mask, u8 val, u8 * data)

{

	int expired = 0;

	struct timer_list status_timer =

	    TIMER_INITIALIZER(tpm_time_expired, jiffies + 10 * HZ,

			      (unsigned long) &expired);

	unsigned long stop;



	/* status immediately available check */

	*data = inb(chip->vendor->base + NSC_STATUS);
@@ -66,17 +63,14 @@ static int wait_for_stat(struct tpm_chip *chip, u8 mask, u8 val, u8 * data) 
		return 0;



	/* wait for status */

	add_timer(&status_timer);

	stop = jiffies + 10 * HZ;

	do {

		set_current_state(TASK_UNINTERRUPTIBLE);

		schedule_timeout(TPM_TIMEOUT);

		msleep(TPM_TIMEOUT);

		*data = inb(chip->vendor->base + 1);

		if ((*data & mask) == val) {

			del_singleshot_timer_sync(&status_timer);

		if ((*data & mask) == val)

			return 0;

	}

	}

	while (!expired);

	while (time_before(jiffies, stop));



	return -EBUSY;

}
@@ -84,10 +78,7 @@ static int wait_for_stat(struct tpm_chip *chip, u8 mask, u8 val, u8 * data) 
static int nsc_wait_for_ready(struct tpm_chip *chip)

{

	int status;

	int expired = 0;

	struct timer_list status_timer =

	    TIMER_INITIALIZER(tpm_time_expired, jiffies + 100,

			      (unsigned long) &expired);

	unsigned long stop;



	/* status immediately available check */

	status = inb(chip->vendor->base + NSC_STATUS);
@@ -97,19 +88,16 @@ static int nsc_wait_for_ready(struct tpm_chip *chip) 
		return 0;



	/* wait for status */

	add_timer(&status_timer);

	stop = jiffies + 100;

	do {

		set_current_state(TASK_UNINTERRUPTIBLE);

		schedule_timeout(TPM_TIMEOUT);

		msleep(TPM_TIMEOUT);

		status = inb(chip->vendor->base + NSC_STATUS);

		if (status & NSC_STATUS_OBF)

			status = inb(chip->vendor->base + NSC_DATA);

		if (status & NSC_STATUS_RDY) {

			del_singleshot_timer_sync(&status_timer);

		if (status & NSC_STATUS_RDY)

			return 0;

	}

	}

	while (!expired);

	while (time_before(jiffies, stop));



	dev_info(&chip->pci_dev->dev, "wait for ready failed\n");

	return -EBUSY;