[PATCH 16/16] hold bus_mutex in netlink and search

David Fries
2014-01-15T05:03:07Z

The bus_mutex needs to be taken to serialize access to a specific bus.
netlink wasn't updated when bus_mutex was added and was calling
without that lock held, and not all of the masters were holding the
bus_mutex in a search. This was causing the ds2490 hardware to stop
responding when both netlink and /sys slaves were executing bus
commands at the same time.

Signed-off-by: David Fries <David@Fries.net>
---
This fixes existing bugs, tacking it to the end of the previous patch
series.

drivers/w1/masters/ds1wm.c | 4 +++-
drivers/w1/masters/ds2490.c | 8 ++++++--
drivers/w1/w1_netlink.c | 13 +++++++++++--
3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/w1/masters/ds1wm.c b/drivers/w1/masters/ds1wm.c
index 02df3b1..b077b8b 100644
--- a/drivers/w1/masters/ds1wm.c
+++ b/drivers/w1/masters/ds1wm.c
@@ -326,13 +326,14 @@ static void ds1wm_search(void *data, struct w1_master *master_dev,
unsigned slaves_found = 0;
unsigned int pass = 0;

+ mutex_lock(&master_dev->bus_mutex);
dev_dbg(&ds1wm_data->pdev->dev, "search begin\n");
while (true) {
++pass;
if (pass > 100) {
dev_dbg(&ds1wm_data->pdev->dev,
"too many attempts (100), search aborted\n");
- return;
+ break;
}

mutex_lock(&master_dev->bus_mutex);
@@ -439,6 +440,7 @@ static void ds1wm_search(void *data, struct w1_master *master_dev,
dev_dbg(&ds1wm_data->pdev->dev,
"pass: %d total: %d search done ms d bit pos: %d\n", pass,
slaves_found, ms_discrep_bit);
+ mutex_unlock(&master_dev->bus_mutex);
}

/* --------------------------------------------------------------------- */
diff --git a/drivers/w1/masters/ds2490.c b/drivers/w1/masters/ds2490.c
index db0bf32..7404ad30 100644
--- a/drivers/w1/masters/ds2490.c
+++ b/drivers/w1/masters/ds2490.c
@@ -727,9 +727,11 @@ static void ds9490r_search(void *data, struct w1_master *master,
*/
u64 buf[2*64/8];

+ mutex_lock(&master->bus_mutex);
+
/* address to start searching at */
if (ds_send_data(dev, (u8 *)&master->search_id, 8) < 0)
- return;
+ goto search_out;
master->search_id = 0;

value = COMM_SEARCH_ACCESS | COMM_IM | COMM_RST | COMM_SM | COMM_F |
@@ -739,7 +741,7 @@ static void ds9490r_search(void *data, struct w1_master *master,
search_limit = 0;
index = search_type | (search_limit << 8);
if (ds_send_control(dev, value, index) < 0)
- return;
+ goto search_out;

do {
schedule_timeout(jtime);
@@ -791,6 +793,8 @@ 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);
}

#if 0
diff --git a/drivers/w1/w1_netlink.c b/drivers/w1/w1_netlink.c
index a5dc219..5234964 100644
--- a/drivers/w1/w1_netlink.c
+++ b/drivers/w1/w1_netlink.c
@@ -246,11 +246,16 @@ static int w1_process_command_master(struct w1_master *dev,
{
int err = -EINVAL;

+ /* drop bus_mutex for search (does it's own locking), and add/remove
+ * which doesn't use the bus
+ */
switch (req_cmd->cmd) {
case W1_CMD_SEARCH:
case W1_CMD_ALARM_SEARCH:
case W1_CMD_LIST_SLAVES:
+ mutex_unlock(&dev->bus_mutex);
err = w1_get_slaves(dev, req_msg, req_hdr, req_cmd);
+ mutex_lock(&dev->bus_mutex);
break;
case W1_CMD_READ:
case W1_CMD_WRITE:
@@ -262,8 +267,12 @@ static int w1_process_command_master(struct w1_master *dev,
break;
case W1_CMD_SLAVE_ADD:
case W1_CMD_SLAVE_REMOVE:
+ mutex_unlock(&dev->bus_mutex);
+ mutex_lock(&dev->mutex);
err = w1_process_command_addremove(dev, req_msg, req_hdr,
req_cmd);
+ mutex_unlock(&dev->mutex);
+ mutex_lock(&dev->bus_mutex);
break;
default:
err = -EINVAL;
@@ -400,7 +409,7 @@ static void w1_process_cb(struct w1_master *dev, struct w1_async_cmd *async_cmd)
struct w1_slave *sl = node->sl;
struct w1_netlink_cmd *cmd = NULL;

- mutex_lock(&dev->mutex);
+ mutex_lock(&dev->bus_mutex);
dev->portid = node->block->portid;
if (sl && w1_reset_select_slave(sl))
err = -ENODEV;
@@ -437,7 +446,7 @@ static void w1_process_cb(struct w1_master *dev, struct w1_async_cmd *async_cmd)
else
atomic_dec(&dev->refcnt);
dev->portid = 0;
- mutex_unlock(&dev->mutex);
+ mutex_unlock(&dev->bus_mutex);

mutex_lock(&dev->list_mutex);
list_del(&async_cmd->async_entry);
--
1.7.10.4