[PATCH RFC 3/8] clock device: convert clock_getres

[Richard Cochran]

This patch lets the clock_getres system call use dynamic clock devices.

Signed-off-by: Richard Cochran <richard.coch...@omicron.at>
---
 include/linux/posix-timers.h |    1 +
 kernel/posix-timers.c        |    3 +--
 kernel/time/clockdevice.c    |   27 +++++++++++++++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index 70f40e6..7d6a4f0 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -137,5 +137,6 @@ long clock_nanosleep_restart(struct restart_block 
*restart_block);
 void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new);
 
 int posix_clock_gettime(const clockid_t clock, struct timespec __user *tp);
+int posix_clock_getres(const clockid_t clock, struct timespec __user *tp);
 
 #endif
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 4aecbfa..baa6a2e 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -969,8 +969,7 @@ int posix_clock_gettime(const clockid_t which_clock,
 
 }
 
-SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
-               struct timespec __user *, tp)
+int posix_clock_getres(const clockid_t which_clock, struct timespec __user *tp)
 {
        struct timespec rtn_tp;
        int error;
diff --git a/kernel/time/clockdevice.c b/kernel/time/clockdevice.c
index e80117b..6629ae7 100644
--- a/kernel/time/clockdevice.c
+++ b/kernel/time/clockdevice.c
@@ -211,3 +211,30 @@ SYSCALL_DEFINE2(clock_gettime,
        mutex_unlock(&clk->mux);
        return err;
 }
+
+SYSCALL_DEFINE2(clock_getres,
+               const clockid_t, id, struct timespec __user *, user_ts)
+{
+       struct timespec ts;
+       struct clock_device *clk;
+       int err;
+
+       clk = clockid_to_clock_device(id);
+       if (!clk)
+               return posix_clock_getres(id, user_ts);
+
+       mutex_lock(&clk->mux);
+
+       if (clk->zombie)
+               err = -ENODEV;
+       else if (!clk->ops->clock_getres)
+               err = -EOPNOTSUPP;
+       else
+               err = clk->ops->clock_getres(clk->priv, &ts);
+
+       if (!err && user_ts && copy_to_user(user_ts, &ts, sizeof(ts)))
+               err = -EFAULT;
+
+       mutex_unlock(&clk->mux);
+       return err;
+}
-- 
1.7.0.4

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