Re: [PATCH] tpm: Revert "tpm: fix invalid locking in NONBLOCKING mode"

[Tadeusz Struk]

On 5/26/20 12:14 PM, James Bottomley wrote:
> +     /* atomic tpm command send and result receive. We only hold the ops
> +      * lock during this period so that the tpm can be unregistered even if
> +      * the char dev is held open.
> +      */
> +     if (tpm_try_get_ops(priv->chip)) {
> +             ret = -EPIPE;
> +             goto out;
> +     }
> +
Hi James,
This won't help if the message is read by an async tcti. If the problem lies
in the chip get locality code, perhaps this could help to debug the root-cause
instead of masking it out in the upper layer code:

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 2435216bd10a..da5ecd0376bf 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -202,20 +202,22 @@ static int request_locality(struct tpm_chip *chip, int l)
                return rc;
 
        stop = jiffies + chip->timeout_a;
+       timeout = stop - jiffies;
 
        if (chip->flags & TPM_CHIP_FLAG_IRQ) {
 again:
                timeout = stop - jiffies;
                if ((long)timeout <= 0)
-                       return -1;
+                       goto out;
+
                rc = wait_event_interruptible_timeout(priv->int_queue,
-                                                     (check_locality
-                                                      (chip, l)),
+                                                     check_locality(chip, l),
                                                      timeout);
                if (rc > 0)
                        return l;
                if (rc == -ERESTARTSYS && freezing(current)) {
                        clear_thread_flag(TIF_SIGPENDING);
+                       timeout = stop - jiffies;
                        goto again;
                }
        } else {
@@ -226,6 +228,10 @@ static int request_locality(struct tpm_chip *chip, int l)
                        tpm_msleep(TPM_TIMEOUT);
                } while (time_before(jiffies, stop));
        }
+out:
+       dev_warn(&chip->dev, "%s: failed to request locality %d after %lu ms\n",
+                        __func__, l, timeout * HZ / 1000);
+
        return -1;
 }