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Subject[PATCH 2/2] w1/masters/ds2490: queue up found IDs during scan
Date
Queue up found IDs in a buffer and run the callback once for each found ID
at the end. This is necessary because we hold the bus_mutex during the
whole scan, and some of the "add-device" callbacks deadlock as they
themselves want to mutex_lock(bus_mutex).

Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Christian Vogel <vogelchr@vogel.cx>
---
drivers/w1/masters/ds2490.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/w1/masters/ds2490.c b/drivers/w1/masters/ds2490.c
index e17c8f70dcd0..cd8821580f71 100644
--- a/drivers/w1/masters/ds2490.c
+++ b/drivers/w1/masters/ds2490.c
@@ -688,12 +688,22 @@ static void ds9490r_search(void *data, struct w1_master *master,
* packet size.
*/
const size_t bufsize = 2 * 64;
- u64 *buf;
+ u64 *buf, *found_ids;

buf = kmalloc(bufsize, GFP_KERNEL);
if (!buf)
return;

+ /*
+ * We are holding the bus mutex during the scan, but adding devices via the
+ * callback needs the bus to be unlocked. So we queue up found ids here.
+ */
+ found_ids = kmalloc_array(master->max_slave_count, sizeof(u64), GFP_KERNEL);
+ if (!found_ids) {
+ kfree(buf);
+ return;
+ }
+
mutex_lock(&master->bus_mutex);

/* address to start searching at */
@@ -729,13 +739,13 @@ static void ds9490r_search(void *data, struct w1_master *master,
if (err < 0)
break;
for (i = 0; i < err/8; ++i) {
- ++found;
- if (found <= search_limit)
- callback(master, buf[i]);
+ found_ids[found++] = buf[i];
/* can't know if there will be a discrepancy
* value after until the next id */
- if (found == search_limit)
+ if (found == search_limit) {
master->search_id = buf[i];
+ break;
+ }
}
}

@@ -759,9 +769,14 @@ static void ds9490r_search(void *data, struct w1_master *master,
master->max_slave_count);
set_bit(W1_WARN_MAX_COUNT, &master->flags);
}
+
search_out:
mutex_unlock(&master->bus_mutex);
kfree(buf);
+
+ for (i = 0; i < found; i++) /* run callback for all queued up IDs */
+ callback(master, found_ids[i]);
+ kfree(found_ids);
}

#if 0
--
2.30.0
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