From d4ccb132801aeeb2cfd18c4b4b7fa0043ab37f80 Mon Sep 17 00:00:00 2001 From: Eric Lapuyade Date: Mon, 7 May 2012 12:31:15 +0200 Subject: [PATCH] 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 Signed-off-by: Samuel Ortiz Signed-off-by: John W. Linville --- 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 0fcf4a54776b..b7ca4a2a1d72 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 7df28ad4727f..9f6ce011d35d 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 f1829f6ae9c5..77dae74832d3 100644 --- a/net/nfc/netlink.c +++ b/net/nfc/netlink.c @@ -128,7 +128,7 @@ 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; @@ -141,7 +141,7 @@ 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; -- 2.34.1