From: Eric Lapuyade <eric.lapuyade@xxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Samuel Ortiz <sameo@xxxxxxxxxxxxxxx>
---
include/net/nfc/nfc.h | 1 -
net/nfc/core.c | 35 ++++++++++++++++++++++++++---------
net/nfc/netlink.c | 4 ++--
3 files changed, 28 insertions(+), 12 deletions(-)
diff --git a/include/net/nfc/nfc.h b/include/net/nfc/nfc.h
index 8ba1747..cee20aa 100644
--- a/include/net/nfc/nfc.h
+++ b/include/net/nfc/nfc.h
@@ -97,7 +97,6 @@ struct nfc_dev {
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 5d86f6c..02e1fda 100644
--- a/net/nfc/core.c
+++ b/net/nfc/core.c
@@ -501,6 +501,9 @@ EXPORT_SYMBOL(nfc_alloc_recv_skb);
* 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 @@ int nfc_targets_found(struct nfc_dev *dev,
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 @@ int nfc_targets_found(struct nfc_dev *dev,
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 @@ int nfc_targets_found(struct nfc_dev *dev,
}
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 @@ int nfc_target_lost(struct nfc_dev *dev, u32 target_idx)
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 @@ int nfc_target_lost(struct nfc_dev *dev, u32 target_idx)
}
if (i == dev->n_targets) {
- spin_unlock_bh(&dev->targets_lock);
+ device_unlock(&dev->dev);
return -EINVAL;
}
@@ -569,7 +584,7 @@ int nfc_target_lost(struct nfc_dev *dev, u32 target_idx)
dev->targets = NULL;
}
- spin_unlock_bh(&dev->targets_lock);
+ device_unlock(&dev->dev);
nfc_genl_target_lost(dev, target_idx);
@@ -607,8 +622,10 @@ static void nfc_check_pres_work(struct work_struct *work)
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 @@ struct nfc_dev *nfc_allocate_device(struct nfc_ops *ops,
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 6c558bc..cc89e4f 100644
--- a/net/nfc/netlink.c
+++ b/net/nfc/netlink.c
@@ -124,7 +124,7 @@ static int nfc_genl_dump_targets(struct sk_buff *skb,
cb->args[1] = (long) dev;
}
- spin_lock_bh(&dev->targets_lock);
+ device_lock(&dev->dev);
cb->seq = dev->targets_generation;
@@ -137,7 +137,7 @@ static int nfc_genl_dump_targets(struct sk_buff *skb,
i++;
}
- spin_unlock_bh(&dev->targets_lock);
+ device_unlock(&dev->dev);
cb->args[0] = i;
--
1.7.9.1
--
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