| Message ID | 20210816040600.175813-2-bongsu.jeon2@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | Update the virtual NCI driver and the NCI selftests | expand |
On 16/08/2021 06:05, bongsu.jeon2@gmail.com wrote: > From: Bongsu Jeon <bongsu.jeon@samsung.com> > > In previous version, the user level virtual device application that used > this driver should have the polling scheme to read a NCI frame. > To remove this polling scheme, changed the driver code to use Wait Queue. > Subject - please prefix it with: "nfc: virtual_ncidev: " Also make it simpler (skipping unnecessary words like "change", "device driver"), so: "nfc: virtual_ncidev: use wait queue instead of polling" > Signed-off-by: Bongsu Jeon <bongsu.jeon@samsung.com> > --- > drivers/nfc/virtual_ncidev.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/nfc/virtual_ncidev.c b/drivers/nfc/virtual_ncidev.c > index 2ee0ec4bb739..1953904176a2 100644 > --- a/drivers/nfc/virtual_ncidev.c > +++ b/drivers/nfc/virtual_ncidev.c > @@ -10,6 +10,7 @@ > #include <linux/module.h> > #include <linux/miscdevice.h> > #include <linux/mutex.h> > +#include <linux/wait.h> > #include <net/nfc/nci_core.h> > > enum virtual_ncidev_mode { > @@ -27,6 +28,7 @@ enum virtual_ncidev_mode { > NFC_PROTO_ISO15693_MASK) > > static enum virtual_ncidev_mode state; > +static DECLARE_WAIT_QUEUE_HEAD(wq); > static struct miscdevice miscdev; > static struct sk_buff *send_buff; > static struct nci_dev *ndev; > @@ -61,6 +63,7 @@ static int virtual_nci_send(struct nci_dev *ndev, struct sk_buff *skb) > } > send_buff = skb_copy(skb, GFP_KERNEL); > mutex_unlock(&nci_mutex); > + wake_up_interruptible(&wq); > > return 0; > } > @@ -76,12 +79,11 @@ static ssize_t virtual_ncidev_read(struct file *file, char __user *buf, > { > size_t actual_len; > > - mutex_lock(&nci_mutex); > - if (!send_buff) { > - mutex_unlock(&nci_mutex); > + wait_event_interruptible(wq, send_buff); > + if (!send_buff) I think access to send_buff should still be protected by mutex. What happens if you have to readers? > return 0; > - } > > + mutex_lock(&nci_mutex); > actual_len = min_t(size_t, count, send_buff->len); > > if (copy_to_user(buf, send_buff->data, actual_len)) { > Best regards, Krzysztof
diff --git a/drivers/nfc/virtual_ncidev.c b/drivers/nfc/virtual_ncidev.c index 2ee0ec4bb739..1953904176a2 100644 --- a/drivers/nfc/virtual_ncidev.c +++ b/drivers/nfc/virtual_ncidev.c @@ -10,6 +10,7 @@ #include <linux/module.h> #include <linux/miscdevice.h> #include <linux/mutex.h> +#include <linux/wait.h> #include <net/nfc/nci_core.h> enum virtual_ncidev_mode { @@ -27,6 +28,7 @@ enum virtual_ncidev_mode { NFC_PROTO_ISO15693_MASK) static enum virtual_ncidev_mode state; +static DECLARE_WAIT_QUEUE_HEAD(wq); static struct miscdevice miscdev; static struct sk_buff *send_buff; static struct nci_dev *ndev; @@ -61,6 +63,7 @@ static int virtual_nci_send(struct nci_dev *ndev, struct sk_buff *skb) } send_buff = skb_copy(skb, GFP_KERNEL); mutex_unlock(&nci_mutex); + wake_up_interruptible(&wq); return 0; } @@ -76,12 +79,11 @@ static ssize_t virtual_ncidev_read(struct file *file, char __user *buf, { size_t actual_len; - mutex_lock(&nci_mutex); - if (!send_buff) { - mutex_unlock(&nci_mutex); + wait_event_interruptible(wq, send_buff); + if (!send_buff) return 0; - } + mutex_lock(&nci_mutex); actual_len = min_t(size_t, count, send_buff->len); if (copy_to_user(buf, send_buff->data, actual_len)) {