[PATCH] s390: sclp console driver.

From: Martin Schwidefsky (schwidefsky_at_de.ibm.com)
Date: 06/30/04

  • Next message: Martin Schwidefsky: "[PATCH] s390: network driver changes." 
    Date:	Wed, 30 Jun 2004 19:08:10 +0200
To: akpm@osdl.org, linux-kernel@vger.kernel.org

    [PATCH] s390: sclp console driver.

    From: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>

    sclp console driver changes:
     - Correct handling of busy and not operational states.

    Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

    diffstat:
     drivers/s390/char/sclp.c | 69 +++++++++++++++++++++++++++++++----------------
     1 files changed, 46 insertions(+), 23 deletions(-)

    diff -urN linux-2.6/drivers/s390/char/sclp.c linux-2.6-s390/drivers/s390/char/sclp.c
    --- linux-2.6/drivers/s390/char/sclp.c Wed Jun 16 07:19:37 2004
    +++ linux-2.6-s390/drivers/s390/char/sclp.c Wed Jun 30 17:06:36 2004
    @@ -52,6 +52,9 @@
     /* Timer for init mask retries. */
     static struct timer_list retry_timer;
     
    +/* Timer for busy retries. */
    +static struct timer_list sclp_busy_timer;
    +
     static volatile unsigned long sclp_status = 0;
     /* some status flags */
     #define SCLP_INIT 0
    @@ -59,6 +62,7 @@
     #define SCLP_READING 2
     
     #define SCLP_INIT_POLL_INTERVAL 1
    +#define SCLP_BUSY_POLL_INTERVAL 1
     
     #define SCLP_COMMAND_INITIATED 0
     #define SCLP_BUSY 2
    @@ -93,45 +97,61 @@
              */
             if (cc == SCLP_NOT_OPERATIONAL)
                     return -EIO;
    - /*
    - * We set the SCLP_RUNNING bit for cc 2 as well because if
    - * service_call returns cc 2 some old request is running
    - * that has to complete first
    - */
    - set_bit(SCLP_RUNNING, &sclp_status);
             if (cc == SCLP_BUSY)
                     return -EBUSY;
             return 0;
     }
     
    -static int
    +static void
     sclp_start_request(void)
     {
             struct sclp_req *req;
             int rc;
             unsigned long flags;
     
    - /* quick exit if sclp is already in use */
    - if (test_bit(SCLP_RUNNING, &sclp_status))
    - return -EBUSY;
             spin_lock_irqsave(&sclp_lock, flags);
    - /* Get first request on queue if available */
    - req = NULL;
    - if (!list_empty(&sclp_req_queue))
    + /* quick exit if sclp is already in use */
    + if (test_bit(SCLP_RUNNING, &sclp_status)) {
    + spin_unlock_irqrestore(&sclp_lock, flags);
    + return;
    + }
    + /* Try to start requests from the request queue. */
    + while (!list_empty(&sclp_req_queue)) {
                     req = list_entry(sclp_req_queue.next, struct sclp_req, list);
    - if (req) {
                     rc = __service_call(req->command, req->sccb);
    - if (rc) {
    - req->status = SCLP_REQ_FAILED;
    - list_del(&req->list);
    - } else
    + if (rc == 0) {
    + /* Sucessfully started request. */
                             req->status = SCLP_REQ_RUNNING;
    - } else
    - rc = -EINVAL;
    + /* Request active. Set running indication. */
    + set_bit(SCLP_RUNNING, &sclp_status);
    + break;
    + }
    + if (rc == -EBUSY) {
    + /**
    + * SCLP is busy but no request is running.
    + * Try again later.
    + */
    + if (!timer_pending(&sclp_busy_timer) ||
    + !mod_timer(&sclp_busy_timer,
    + jiffies + SCLP_BUSY_POLL_INTERVAL*HZ)) {
    + sclp_busy_timer.function =
    + (void *) sclp_start_request;
    + sclp_busy_timer.expires =
    + jiffies + SCLP_BUSY_POLL_INTERVAL*HZ;
    + add_timer(&sclp_busy_timer);
    + }
    + break;
    + }
    + /* Request failed. */
    + req->status = SCLP_REQ_FAILED;
    + list_del(&req->list);
    + if (req->callback) {
    + spin_unlock_irqrestore(&sclp_lock, flags);
    + req->callback(req, req->callback_data);
    + spin_lock_irqsave(&sclp_lock, flags);
    + }
    + }
             spin_unlock_irqrestore(&sclp_lock, flags);
    - if (rc == -EIO && req->callback != NULL)
    - req->callback(req, req->callback_data);
    - return rc;
     }
     
     static int
    @@ -613,6 +633,8 @@
                      */
                     do {
                             rc = __service_call(req->command, req->sccb);
    + if (rc == 0)
    + set_bit(SCLP_RUNNING, &sclp_status);
                             spin_unlock_irqrestore(&sclp_lock, flags);
                             if (rc == -EIO)
                                     return -ENOSYS;
    @@ -685,6 +707,7 @@
             ctl_set_bit(0, 9);
     
             init_timer(&retry_timer);
    + init_timer(&sclp_busy_timer);
             /* do the initial write event mask */
             rc = sclp_init_mask();
             if (rc == 0) {
    -
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