[PATCH 5.4 067/215] soc: fsl: qbman: Use raw spinlock for cgr_lock

Greg Kroah-Hartman
2024-04-11T10:18:38Z

From: Sean Anderson <sean.anderson@linux.dev>

[ Upstream commit fbec4e7fed89b579f2483041fabf9650fb0dd6bc ]

smp_call_function always runs its callback in hard IRQ context, even on
PREEMPT_RT, where spinlocks can sleep. So we need to use a raw spinlock
for cgr_lock to ensure we aren't waiting on a sleeping task.

Although this bug has existed for a while, it was not apparent until
commit ef2a8d5478b9 ("net: dpaa: Adjust queue depth on rate change")
which invokes smp_call_function_single via qman_update_cgr_safe every
time a link goes up or down.

Fixes: 96f413f47677 ("soc/fsl/qbman: fix issue in qman_delete_cgr_safe()")
CC: stable@vger.kernel.org
Reported-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Closes: https://lore.kernel.org/all/20230323153935.nofnjucqjqnz34ej@skbuf/
Reported-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Closes: https://lore.kernel.org/linux-arm-kernel/87wmsyvclu.fsf@pengutronix.de/
Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Reviewed-by: Camelia Groza <camelia.groza@nxp.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/soc/fsl/qbman/qman.c | 25 ++++++++++++++-----------
1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/soc/fsl/qbman/qman.c b/drivers/soc/fsl/qbman/qman.c
index 52327f0dab986..5144b8c66ac46 100644
--- a/drivers/soc/fsl/qbman/qman.c
+++ b/drivers/soc/fsl/qbman/qman.c
@@ -996,7 +996,7 @@ struct qman_portal {
/* linked-list of CSCN handlers. */
struct list_head cgr_cbs;
/* list lock */
- spinlock_t cgr_lock;
+ raw_spinlock_t cgr_lock;
struct work_struct congestion_work;
struct work_struct mr_work;
char irqname[MAX_IRQNAME];
@@ -1286,7 +1286,7 @@ static int qman_create_portal(struct qman_portal *portal,
/* if the given mask is NULL, assume all CGRs can be seen */
qman_cgrs_fill(&portal->cgrs[0]);
INIT_LIST_HEAD(&portal->cgr_cbs);
- spin_lock_init(&portal->cgr_lock);
+ raw_spin_lock_init(&portal->cgr_lock);
INIT_WORK(&portal->congestion_work, qm_congestion_task);
INIT_WORK(&portal->mr_work, qm_mr_process_task);
portal->bits = 0;
@@ -1461,11 +1461,14 @@ static void qm_congestion_task(struct work_struct *work)
union qm_mc_result *mcr;
struct qman_cgr *cgr;

- spin_lock_irq(&p->cgr_lock);
+ /*
+ * FIXME: QM_MCR_TIMEOUT is 10ms, which is too long for a raw spinlock!
+ */
+ raw_spin_lock_irq(&p->cgr_lock);
qm_mc_start(&p->p);
qm_mc_commit(&p->p, QM_MCC_VERB_QUERYCONGESTION);
if (!qm_mc_result_timeout(&p->p, &mcr)) {
- spin_unlock_irq(&p->cgr_lock);
+ raw_spin_unlock_irq(&p->cgr_lock);
dev_crit(p->config->dev, "QUERYCONGESTION timeout\n");
qman_p_irqsource_add(p, QM_PIRQ_CSCI);
return;
@@ -1481,7 +1484,7 @@ static void qm_congestion_task(struct work_struct *work)
list_for_each_entry(cgr, &p->cgr_cbs, node)
if (cgr->cb && qman_cgrs_get(&c, cgr->cgrid))
cgr->cb(p, cgr, qman_cgrs_get(&rr, cgr->cgrid));
- spin_unlock_irq(&p->cgr_lock);
+ raw_spin_unlock_irq(&p->cgr_lock);
qman_p_irqsource_add(p, QM_PIRQ_CSCI);
}

@@ -2438,7 +2441,7 @@ int qman_create_cgr(struct qman_cgr *cgr, u32 flags,
preempt_enable();

cgr->chan = p->config->channel;
- spin_lock_irq(&p->cgr_lock);
+ raw_spin_lock_irq(&p->cgr_lock);

if (opts) {
struct qm_mcc_initcgr local_opts = *opts;
@@ -2475,7 +2478,7 @@ int qman_create_cgr(struct qman_cgr *cgr, u32 flags,
qman_cgrs_get(&p->cgrs[1], cgr->cgrid))
cgr->cb(p, cgr, 1);
out:
- spin_unlock_irq(&p->cgr_lock);
+ raw_spin_unlock_irq(&p->cgr_lock);
put_affine_portal();
return ret;
}
@@ -2510,7 +2513,7 @@ int qman_delete_cgr(struct qman_cgr *cgr)
return -EINVAL;

memset(&local_opts, 0, sizeof(struct qm_mcc_initcgr));
- spin_lock_irqsave(&p->cgr_lock, irqflags);
+ raw_spin_lock_irqsave(&p->cgr_lock, irqflags);
list_del(&cgr->node);
/*
* If there are no other CGR objects for this CGRID in the list,
@@ -2535,7 +2538,7 @@ int qman_delete_cgr(struct qman_cgr *cgr)
/* add back to the list */
list_add(&cgr->node, &p->cgr_cbs);
release_lock:
- spin_unlock_irqrestore(&p->cgr_lock, irqflags);
+ raw_spin_unlock_irqrestore(&p->cgr_lock, irqflags);
put_affine_portal();
return ret;
}
@@ -2575,9 +2578,9 @@ static int qman_update_cgr(struct qman_cgr *cgr, struct qm_mcc_initcgr *opts)
if (!p)
return -EINVAL;

- spin_lock_irqsave(&p->cgr_lock, irqflags);
+ raw_spin_lock_irqsave(&p->cgr_lock, irqflags);
ret = qm_modify_cgr(cgr, 0, opts);
- spin_unlock_irqrestore(&p->cgr_lock, irqflags);
+ raw_spin_unlock_irqrestore(&p->cgr_lock, irqflags);
put_affine_portal();
return ret;
}
--
2.43.0