Le 22/02/2024 à 18:07, Sean Anderson a écrit : > [Vous ne recevez pas souvent de courriers de sean.anderson@xxxxxxxxx. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ] > > cgr_lock may be locked with interrupts already disabled by > smp_call_function_single. As such, we must use a raw spinlock to avoid > problems on PREEMPT_RT kernels. 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. Why a raw spinlock to avoid problems on PREEMPT_RT, can you elaborate ? If the problem is that interrupts are already disabled, shouldn't you just change the spin_lock_irq() by spin_lock_irqsave() ? Christophe > > Fixes: 96f413f47677 ("soc/fsl/qbman: fix issue in qman_delete_cgr_safe()") > CC: stable@xxxxxxxxxxxxxxx > Reported-by: Vladimir Oltean <vladimir.oltean@xxxxxxx> > Closes: https://lore.kernel.org/all/20230323153935.nofnjucqjqnz34ej@skbuf/ > Reported-by: Steffen Trumtrar <s.trumtrar@xxxxxxxxxxxxxx> > Closes: https://lore.kernel.org/linux-arm-kernel/87wmsyvclu.fsf@xxxxxxxxxxxxxx/ > Signed-off-by: Sean Anderson <sean.anderson@xxxxxxxxx> > Reviewed-by: Camelia Groza <camelia.groza@xxxxxxx> > Tested-by: Vladimir Oltean <vladimir.oltean@xxxxxxx> > > --- > > Changes in v4: > - Add a note about how raw spinlocks aren't quite right > > Changes in v3: > - Change blamed commit to something more appropriate > > 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 1bf1f1ea67f0..7e9074519ad2 100644 > --- a/drivers/soc/fsl/qbman/qman.c > +++ b/drivers/soc/fsl/qbman/qman.c > @@ -991,7 +991,7 @@ 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]; > @@ -1281,7 +1281,7 @@ 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; > @@ -1456,11 +1456,14 @@ 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; > @@ -1476,7 +1479,7 @@ 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); > } > > @@ -2440,7 +2443,7 @@ 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; > @@ -2477,7 +2480,7 @@ 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; > } > @@ -2512,7 +2515,7 @@ 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, > @@ -2537,7 +2540,7 @@ 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; > } > @@ -2577,9 +2580,9 @@ 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; > } > -- > 2.35.1.1320.gc452695387.dirty >
