ntsync: Introduce NTSYNC_IOC_SEM_READ.

This corresponds to the NT syscall NtQuerySemaphore().

This returns the current count and maximum count of the semaphore.

Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
Link: https://lore.kernel.org/r/20241213193511.457338-13-zfigura@codeweavers.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c
index 141ebe8a7d4f0f56e220c2a5e6822ecd4c290899..b2043412c5cd3ae38d14887a3c0280acc089fd16 100644 (file)
--- a/drivers/misc/ntsync.c
+++ b/drivers/misc/ntsync.c
@@ -583,6 +583,28 @@ static int ntsync_event_reset(struct ntsync_obj *event, void __user *argp)
        return 0;
 }
 
+static int ntsync_sem_read(struct ntsync_obj *sem, void __user *argp)
+{
+       struct ntsync_sem_args __user *user_args = argp;
+       struct ntsync_device *dev = sem->dev;
+       struct ntsync_sem_args args;
+       bool all;
+
+       if (sem->type != NTSYNC_TYPE_SEM)
+               return -EINVAL;
+
+       all = ntsync_lock_obj(dev, sem);
+
+       args.count = sem->u.sem.count;
+       args.max = sem->u.sem.max;
+
+       ntsync_unlock_obj(dev, sem, all);
+
+       if (copy_to_user(user_args, &args, sizeof(args)))
+               return -EFAULT;
+       return 0;
+}
+
 static int ntsync_obj_release(struct inode *inode, struct file *file)
 {
        struct ntsync_obj *obj = file->private_data;
@@ -602,6 +624,8 @@ static long ntsync_obj_ioctl(struct file *file, unsigned int cmd,
        switch (cmd) {
        case NTSYNC_IOC_SEM_RELEASE:
                return ntsync_sem_release(obj, argp);
+       case NTSYNC_IOC_SEM_READ:
+               return ntsync_sem_read(obj, argp);
        case NTSYNC_IOC_MUTEX_UNLOCK:
                return ntsync_mutex_unlock(obj, argp);
        case NTSYNC_IOC_MUTEX_KILL:

diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h
index 9eab7666b8b99a565a6081c957d9bce9523cb08b..e36b4cfb7d34695201749f129748ce845da53078 100644 (file)
--- a/include/uapi/linux/ntsync.h
+++ b/include/uapi/linux/ntsync.h
@@ -51,5 +51,6 @@ struct ntsync_wait_args {
 #define NTSYNC_IOC_EVENT_SET           _IOR ('N', 0x88, __u32)
 #define NTSYNC_IOC_EVENT_RESET         _IOR ('N', 0x89, __u32)
 #define NTSYNC_IOC_EVENT_PULSE         _IOR ('N', 0x8a, __u32)
+#define NTSYNC_IOC_SEM_READ            _IOR ('N', 0x8b, struct ntsync_sem_args)
 
 #endif