Currently access to hardware stats buffer isn't protected, this can
result in multiple writes and reads at the same time to the same
memory location. This can lead to providing an incorrect value to
the user. Add a mutex to protect against it.
Fixes: b40f4757daa1 ("IB/core: Make device counter infrastructure dynamic")
Signed-off-by: Mark Bloch <markb@xxxxxxxxxxxx>
---
We might want to protect setting/reading lifespan as well, but it seems
not needed as it shouldn't be changed too often, and even if it does not by
multiple threads at the same time.
v0 -> v1: Removed RFC tag and added a Fixes line.
---
drivers/infiniband/core/sysfs.c | 10 ++++++++--
include/rdma/ib_verbs.h | 1 +
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/infiniband/core/sysfs.c b/drivers/infiniband/core/sysfs.c
index 8ae1308e..b769d61 100644
--- a/drivers/infiniband/core/sysfs.c
+++ b/drivers/infiniband/core/sysfs.c
@@ -810,10 +810,15 @@ static ssize_t show_hw_stats(struct kobject *kobj, struct attribute *attr,
dev = port->ibdev;
stats = port->hw_stats;
}
+ mutex_lock(&stats->lock);
ret = update_hw_stats(dev, stats, hsa->port_num, hsa->index);
if (ret)
- return ret;
- return print_hw_stat(stats, hsa->index, buf);
+ goto unlock;
+ ret = print_hw_stat(stats, hsa->index, buf);
+unlock:
+ mutex_unlock(&stats->lock);
+
+ return ret;
}
static ssize_t show_stats_lifespan(struct kobject *kobj,
@@ -951,6 +956,7 @@ static void setup_hw_stats(struct ib_device *device, struct ib_port *port,
sysfs_attr_init(hsag->attrs[i]);
}
+ mutex_init(&stats->lock);
/* treat an error here as non-fatal */
hsag->attrs[i] = alloc_hsa_lifespan("lifespan", port_num);
if (hsag->attrs[i])
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 73b2387..33fbccb 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -484,6 +484,7 @@ enum ib_port_speed {
* filled in by the drivers get_stats routine
*/
struct rdma_hw_stats {
+ struct mutex lock;
unsigned long timestamp;
unsigned long lifespan;
const char * const *names;
--
1.8.4.3
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