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Subject[PATCH 5/5] fsi: Prevent multiple concurrent rescans
Date
The bus scanning process isn't terribly good at parallel attempts
at rescanning the same bus. Let's have a per-master mutex protecting
the scanning process.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
drivers/fsi/fsi-core.c | 16 ++++++++++++++--
drivers/fsi/fsi-master.h | 2 ++
2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index dea5bd48acc5..2c31563fdcae 100644
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -1203,8 +1203,14 @@ static void fsi_master_unscan(struct fsi_master *master)

int fsi_master_rescan(struct fsi_master *master)
{
+ int rc;
+
+ mutex_lock(&master->scan_lock);
fsi_master_unscan(master);
- return fsi_master_scan(master);
+ rc = fsi_master_scan(master);
+ mutex_unlock(&master->scan_lock);
+
+ return rc;
}
EXPORT_SYMBOL_GPL(fsi_master_rescan);

@@ -1240,6 +1246,7 @@ int fsi_master_register(struct fsi_master *master)
int rc;
struct device_node *np;

+ mutex_init(&master->scan_lock);
master->idx = ida_simple_get(&master_ida, 0, INT_MAX, GFP_KERNEL);
dev_set_name(&master->dev, "fsi%d", master->idx);

@@ -1264,8 +1271,11 @@ int fsi_master_register(struct fsi_master *master)
}

np = dev_of_node(&master->dev);
- if (!of_property_read_bool(np, "no-scan-on-init"))
+ if (!of_property_read_bool(np, "no-scan-on-init")) {
+ mutex_lock(&master->scan_lock);
fsi_master_scan(master);
+ mutex_unlock(&master->scan_lock);
+ }

return 0;
}
@@ -1278,7 +1288,9 @@ void fsi_master_unregister(struct fsi_master *master)
master->idx = -1;
}

+ mutex_lock(&master->scan_lock);
fsi_master_unscan(master);
+ mutex_unlock(&master->scan_lock);
device_unregister(&master->dev);
}
EXPORT_SYMBOL_GPL(fsi_master_unregister);
diff --git a/drivers/fsi/fsi-master.h b/drivers/fsi/fsi-master.h
index f653f75da7be..040a7d4cf717 100644
--- a/drivers/fsi/fsi-master.h
+++ b/drivers/fsi/fsi-master.h
@@ -18,6 +18,7 @@
#define DRIVERS_FSI_MASTER_H

#include <linux/device.h>
+#include <linux/mutex.h>

/* Various protocol delays */
#define FSI_ECHO_DELAY_CLOCKS 16 /* Number clocks for echo delay */
@@ -59,6 +60,7 @@ struct fsi_master {
int idx;
int n_links;
int flags;
+ struct mutex scan_lock;
int (*read)(struct fsi_master *, int link, uint8_t id,
uint32_t addr, void *val, size_t size);
int (*write)(struct fsi_master *, int link, uint8_t id,
--
2.17.1
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