Rx interrupt enable and disable wait for reset_ops_lock and then return -EBUSY if a reset is in progress. The reset thread holds that lock across the teardown (mana_dev_stop(), the RESET_ENTER request to secondary processes, mana_dev_close()) and across the re-probe, and each request to the secondaries may take up to MANA_MP_REQ_TIMEOUT_SEC. An lcore that calls rx_intr_enable or rx_intr_disable during one of those steps blocks for that long, only to get -EBUSY.
Retry the trylock while the device is active, yielding the CPU in between, and return -EBUSY as soon as it is not. Outside a reset the lock is held by another queue's Rx interrupt call or by a control operation. The data path must already be stopped before dev_stop/dev_close, so the wait is short in a correct application. Suggested-by: Wei Hu <[email protected]> Signed-off-by: Orgad Shaneh <[email protected]> --- v2: - Yield with sched_yield() instead of rte_pause(), so a preempted lock holder on the same CPU can run (Stephen). - Fix the commit message and comment: outside a reset the lock is also held by control operations, so the wait is short only in an application that stops the data path before dev_stop/dev_close. Applies on next-net for-main, on top of efa36b47334d ("net/mana: fix Rx interrupt enable failing on lock contention"). Squash it into that commit if you prefer. Builds with meson -Dwerror=true (gcc 14, rdma-core 56). A MANA reset cannot be triggered on demand on Azure, so the reset path is untested. The rwlock (tryrdlock in rx_intr, write lock in control ops and the reset thread) fits the burst_state follow-up for main; I'll look at it there. drivers/net/mana/mana.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/drivers/net/mana/mana.c b/drivers/net/mana/mana.c index f624cde6b9..71a3fd20d7 100644 --- a/drivers/net/mana/mana.c +++ b/drivers/net/mana/mana.c @@ -2,6 +2,7 @@ * Copyright 2022 Microsoft Corporation */ +#include <sched.h> #include <unistd.h> #include <dirent.h> #include <fcntl.h> @@ -451,14 +452,24 @@ mana_reset_trylock(struct mana_priv *priv) } /* - * Like mana_reset_trylock(), but wait for the lock. Used by Rx interrupt - * enable/disable, which every queue calls on each sleep and wakeup: they - * must not fail just because another queue holds the lock for a moment. + * Like mana_reset_trylock(), but wait while the device is active. Used by + * Rx interrupt enable/disable, which every queue calls on each sleep and + * wakeup: they must not fail just because another queue holds the lock + * for a moment. Outside a reset the lock is held by another queue's Rx + * interrupt call or by a control operation; the data path must be stopped + * before dev_stop/dev_close, so in a correct application the wait is + * short. Once a reset has started, fail at once instead of waiting for + * its teardown or re-probe step. */ static int mana_reset_lock(struct mana_priv *priv) { - pthread_mutex_lock(&priv->reset_ops_lock); + while (pthread_mutex_trylock(&priv->reset_ops_lock)) { + if (rte_atomic_load_explicit(&priv->dev_state, + rte_memory_order_relaxed) != MANA_DEV_ACTIVE) + return -EBUSY; + sched_yield(); + } if (rte_atomic_load_explicit(&priv->dev_state, rte_memory_order_acquire) != MANA_DEV_ACTIVE) { -- 2.52.0
