Commit b8cb86fd authored Nov 10, 2016 by Arnd Bergmann Committed by Greg Kroah-Hartman Nov 14, 2016

staging: lustre: ldlm: pl_recalc time handling is wrong



James Simmons reports:
> The ldlm_pool field pl_recalc_time is set to the current
> monotonic clock value but the interval period is calculated
> with the wall clock. This means the interval period will
> always be far larger than the pl_recalc_period, which is
> just a small interval time period. The correct thing to
> do is to use monotomic clock current value instead of the
> wall clocks value when calculating recalc_interval_sec.

This broke when I converted the 32-bit get_seconds() into
ktime_get_{real_,}seconds() inconsistently. Either
one of those two would have worked, but mixing them
does not.

Staying with the original intention of the patch, this
changes the ktime_get_seconds() calls into ktime_get_real_seconds(),
using real time instead of mononic time.

Cc: stable@vger.kernel.org # v4.4+
Fixes: 8f83409c ("staging/lustre: use 64-bit time for pl_recalc")
Reported-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 46468f03

drivers/staging/lustre/lustre/ldlm/ldlm_pool.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -356,10 +356,10 @@ static int ldlm_pool_recalc(struct ldlm_pool *pl)
		u32 recalc_interval_sec;
		int count;

		recalc_interval_sec = ktime_get_seconds() - pl->pl_recalc_time;
		recalc_interval_sec = ktime_get_real_seconds() - pl->pl_recalc_time;
		if (recalc_interval_sec > 0) {
		spin_lock(&pl->pl_lock);
		recalc_interval_sec = ktime_get_seconds() - pl->pl_recalc_time;
		recalc_interval_sec = ktime_get_real_seconds() - pl->pl_recalc_time;

		if (recalc_interval_sec > 0) {
		/*
		@@ -382,7 +382,7 @@ static int ldlm_pool_recalc(struct ldlm_pool *pl)
		count);
		}

		recalc_interval_sec = pl->pl_recalc_time - ktime_get_seconds() +
		recalc_interval_sec = pl->pl_recalc_time - ktime_get_real_seconds() +
		pl->pl_recalc_period;
		if (recalc_interval_sec <= 0) {
		/* DEBUG: should be re-removed after LU-4536 is fixed */
		@@ -657,7 +657,7 @@ int ldlm_pool_init(struct ldlm_pool pl, struct ldlm_namespace ns,

		spin_lock_init(&pl->pl_lock);
		atomic_set(&pl->pl_granted, 0);
		pl->pl_recalc_time = ktime_get_seconds();
		pl->pl_recalc_time = ktime_get_real_seconds();
		atomic_set(&pl->pl_lock_volume_factor, 1);

		atomic_set(&pl->pl_grant_rate, 0);

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