NFC: Specify usage for targets found and target lost events
It is now specified that nfc_target_found() and nfc_target_lost() core
functions must not be called from an atomic context. This allow us to
serialize calls and protect the targets table using the nfc device lock
instead of a spinlock.
Signed-off-by: Eric Lapuyade <eric.lapuyade@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/net/nfc/nfc.h b/include/net/nfc/nfc.h
index 0fcf4a5..b7ca4a2 100644
--- a/include/net/nfc/nfc.h
+++ b/include/net/nfc/nfc.h
@@ -97,7 +97,6 @@
struct nfc_target *targets;
int n_targets;
int targets_generation;
- spinlock_t targets_lock;
struct device dev;
bool dev_up;
bool polling;
diff --git a/net/nfc/core.c b/net/nfc/core.c
index 7df28ad..9f6ce01 100644
--- a/net/nfc/core.c
+++ b/net/nfc/core.c
@@ -501,6 +501,9 @@
* The device driver must call this function when one or many nfc targets
* are found. After calling this function, the device driver must stop
* polling for targets.
+ * IMPORTANT: this function must not be called from an atomic context.
+ * In addition, it must also not be called from a context that would prevent
+ * the NFC Core to call other nfc ops entry point concurrently.
*/
int nfc_targets_found(struct nfc_dev *dev,
struct nfc_target *targets, int n_targets)
@@ -514,7 +517,7 @@
for (i = 0; i < n_targets; i++)
targets[i].idx = dev->target_next_idx++;
- spin_lock_bh(&dev->targets_lock);
+ device_lock(&dev->dev);
dev->targets_generation++;
@@ -524,12 +527,12 @@
if (!dev->targets) {
dev->n_targets = 0;
- spin_unlock_bh(&dev->targets_lock);
+ device_unlock(&dev->dev);
return -ENOMEM;
}
dev->n_targets = n_targets;
- spin_unlock_bh(&dev->targets_lock);
+ device_unlock(&dev->dev);
nfc_genl_targets_found(dev);
@@ -537,6 +540,18 @@
}
EXPORT_SYMBOL(nfc_targets_found);
+/**
+ * nfc_target_lost - inform that an activated target went out of field
+ *
+ * @dev: The nfc device that had the activated target in field
+ * @target_idx: the nfc index of the target
+ *
+ * The device driver must call this function when the activated target
+ * goes out of the field.
+ * IMPORTANT: this function must not be called from an atomic context.
+ * In addition, it must also not be called from a context that would prevent
+ * the NFC Core to call other nfc ops entry point concurrently.
+ */
int nfc_target_lost(struct nfc_dev *dev, u32 target_idx)
{
struct nfc_target *tg;
@@ -544,7 +559,7 @@
pr_debug("dev_name %s n_target %d\n", dev_name(&dev->dev), target_idx);
- spin_lock_bh(&dev->targets_lock);
+ device_lock(&dev->dev);
for (i = 0; i < dev->n_targets; i++) {
tg = &dev->targets[i];
@@ -553,7 +568,7 @@
}
if (i == dev->n_targets) {
- spin_unlock_bh(&dev->targets_lock);
+ device_unlock(&dev->dev);
return -EINVAL;
}
@@ -569,7 +584,7 @@
dev->targets = NULL;
}
- spin_unlock_bh(&dev->targets_lock);
+ device_unlock(&dev->dev);
nfc_genl_target_lost(dev, target_idx);
@@ -607,8 +622,10 @@
mod_timer(&dev->check_pres_timer, jiffies +
msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
} else {
- nfc_target_lost(dev, dev->active_target->idx);
- dev->active_target = NULL;
+ u32 active_target_idx = dev->active_target->idx;
+ device_unlock(&dev->dev);
+ nfc_target_lost(dev, active_target_idx);
+ return;
}
}
@@ -681,9 +698,9 @@
dev->tx_headroom = tx_headroom;
dev->tx_tailroom = tx_tailroom;
- spin_lock_init(&dev->targets_lock);
nfc_genl_data_init(&dev->genl_data);
+
/* first generation must not be 0 */
dev->targets_generation = 1;
diff --git a/net/nfc/netlink.c b/net/nfc/netlink.c
index f1829f6..77dae74 100644
--- a/net/nfc/netlink.c
+++ b/net/nfc/netlink.c
@@ -128,7 +128,7 @@
cb->args[1] = (long) dev;
}
- spin_lock_bh(&dev->targets_lock);
+ device_lock(&dev->dev);
cb->seq = dev->targets_generation;
@@ -141,7 +141,7 @@
i++;
}
- spin_unlock_bh(&dev->targets_lock);
+ device_unlock(&dev->dev);
cb->args[0] = i;