4.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mark Rutland mark.rutland@arm.com
[ Upstream commit 1898eb61fbc9703efee886d3abec27a388cf28c3 ]
The ARM CCN PMU driver uses dev_warn() to complain about parameters in the user-provided perf_event_attr. This means that under normal operation (e.g. a single invocation of the perf tool), a number of messages warnings may be logged to dmesg.
Tools may issue multiple syscalls to probe for feature support, and multiple applications (from multiple users) can attempt to open events simultaneously, so this is not very helpful, even if a user happens to have access to dmesg. Worse, this can push important information out of the dmesg ring buffer, and can significantly slow down syscall fuzzers, vastly increasing the time it takes to find critical bugs.
Demote the dev_warn() instances to dev_dbg(), as is the case for all other PMU drivers under drivers/perf/. Users who wish to debug PMU event initialisation can enable dynamic debug to receive these messages.
Signed-off-by: Mark Rutland mark.rutland@arm.com Cc: Pawel Moll pawel.moll@arm.com Cc: Will Deacon will.deacon@arm.com Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/perf/arm-ccn.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-)
--- a/drivers/perf/arm-ccn.c +++ b/drivers/perf/arm-ccn.c @@ -736,7 +736,7 @@ static int arm_ccn_pmu_event_init(struct ccn = pmu_to_arm_ccn(event->pmu);
if (hw->sample_period) { - dev_warn(ccn->dev, "Sampling not supported!\n"); + dev_dbg(ccn->dev, "Sampling not supported!\n"); return -EOPNOTSUPP; }
@@ -744,12 +744,12 @@ static int arm_ccn_pmu_event_init(struct event->attr.exclude_kernel || event->attr.exclude_hv || event->attr.exclude_idle || event->attr.exclude_host || event->attr.exclude_guest) { - dev_warn(ccn->dev, "Can't exclude execution levels!\n"); + dev_dbg(ccn->dev, "Can't exclude execution levels!\n"); return -EINVAL; }
if (event->cpu < 0) { - dev_warn(ccn->dev, "Can't provide per-task data!\n"); + dev_dbg(ccn->dev, "Can't provide per-task data!\n"); return -EOPNOTSUPP; } /* @@ -771,13 +771,13 @@ static int arm_ccn_pmu_event_init(struct switch (type) { case CCN_TYPE_MN: if (node_xp != ccn->mn_id) { - dev_warn(ccn->dev, "Invalid MN ID %d!\n", node_xp); + dev_dbg(ccn->dev, "Invalid MN ID %d!\n", node_xp); return -EINVAL; } break; case CCN_TYPE_XP: if (node_xp >= ccn->num_xps) { - dev_warn(ccn->dev, "Invalid XP ID %d!\n", node_xp); + dev_dbg(ccn->dev, "Invalid XP ID %d!\n", node_xp); return -EINVAL; } break; @@ -785,11 +785,11 @@ static int arm_ccn_pmu_event_init(struct break; default: if (node_xp >= ccn->num_nodes) { - dev_warn(ccn->dev, "Invalid node ID %d!\n", node_xp); + dev_dbg(ccn->dev, "Invalid node ID %d!\n", node_xp); return -EINVAL; } if (!arm_ccn_pmu_type_eq(type, ccn->node[node_xp].type)) { - dev_warn(ccn->dev, "Invalid type 0x%x for node %d!\n", + dev_dbg(ccn->dev, "Invalid type 0x%x for node %d!\n", type, node_xp); return -EINVAL; } @@ -808,19 +808,19 @@ static int arm_ccn_pmu_event_init(struct if (event_id != e->event) continue; if (e->num_ports && port >= e->num_ports) { - dev_warn(ccn->dev, "Invalid port %d for node/XP %d!\n", + dev_dbg(ccn->dev, "Invalid port %d for node/XP %d!\n", port, node_xp); return -EINVAL; } if (e->num_vcs && vc >= e->num_vcs) { - dev_warn(ccn->dev, "Invalid vc %d for node/XP %d!\n", + dev_dbg(ccn->dev, "Invalid vc %d for node/XP %d!\n", vc, node_xp); return -EINVAL; } valid = 1; } if (!valid) { - dev_warn(ccn->dev, "Invalid event 0x%x for node/XP %d!\n", + dev_dbg(ccn->dev, "Invalid event 0x%x for node/XP %d!\n", event_id, node_xp); return -EINVAL; }