[RFC 12/12][PATCH] SCHED_DEADLINE: modified sched_*_ex API

[Raistlin]

This commit amends the new API introduced to deal with the new sched_param_ex
scheduling parameter data structure.

What we add is one more parameter to all the functions, containing the size of
sched_param_ex. It might turn out useful in possible future extensions of
sched_param_ex itself, to avoid issue with ABI of legacy applications.

Signed-off-by: Raistlin <raistlin@xxxxxxxx>
---
 include/linux/syscalls.h |    6 +++---
 kernel/sched.c           |   25 ++++++++++++++++---------
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index e01f59c..60a99a7 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -391,16 +391,16 @@ asmlinkage long sys_clock_nanosleep(clockid_t which_clock, int flags,
 asmlinkage long sys_nice(int increment);
 asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
 					struct sched_param __user *param);
-asmlinkage long sys_sched_setscheduler_ex(pid_t pid, int policy,
+asmlinkage long sys_sched_setscheduler_ex(pid_t pid, int policy, unsigned len,
 					struct sched_param_ex __user *param);
 asmlinkage long sys_sched_setparam(pid_t pid,
 					struct sched_param __user *param);
-asmlinkage long sys_sched_setparam_ex(pid_t pid,
+asmlinkage long sys_sched_setparam_ex(pid_t pid, unsigned len,
 					struct sched_param_ex __user *param);
 asmlinkage long sys_sched_getscheduler(pid_t pid);
 asmlinkage long sys_sched_getparam(pid_t pid,
 					struct sched_param __user *param);
-asmlinkage long sys_sched_getparam_ex(pid_t pid,
+asmlinkage long sys_sched_getparam_ex(pid_t pid, unsigned len,
 					struct sched_param_ex __user *param);
 asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
 					unsigned long __user *user_mask_ptr);
diff --git a/kernel/sched.c b/kernel/sched.c
index a8ebfa2..d3a61f5 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6662,7 +6662,7 @@ do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
 }
 
 static int
-do_sched_setscheduler_ex(pid_t pid, int policy,
+do_sched_setscheduler_ex(pid_t pid, int policy, unsigned int len,
 			 struct sched_param_ex __user *param_ex)
 {
 	struct sched_param lparam;
@@ -6672,8 +6672,9 @@ do_sched_setscheduler_ex(pid_t pid, int policy,
 
 	if (!param_ex || pid < 0)
 		return -EINVAL;
-	if (copy_from_user(&lparam_ex, param_ex,
-	    sizeof(struct sched_param_ex)))
+	if (len > sizeof(struct sched_param_ex))
+		return -EINVAL;
+	if (copy_from_user(&lparam_ex, param_ex,len))
 		return -EFAULT;
 
 	rcu_read_lock();
@@ -6708,15 +6709,17 @@ SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
  * sys_sched_setscheduler_ex - set/change the scheduler policy to SCHED_DEADLINE
  * @pid: the pid in question.
  * @policy: new policy (should be SCHED_DEADLINE).
+ * @len: size of data pointed by param_ex.
  * @param: structure containg the extended deadline parameters.
  */
-SYSCALL_DEFINE3(sched_setscheduler_ex, pid_t, pid, int, policy,
+SYSCALL_DEFINE4(sched_setscheduler_ex, pid_t, pid,
+		int, policy, unsigned, len,
 		struct sched_param_ex __user *, param_ex)
 {
 	if (policy < 0)
 		return -EINVAL;
 
-	return do_sched_setscheduler_ex(pid, policy, param_ex);
+	return do_sched_setscheduler_ex(pid, policy, len, param_ex);
 }
 
 /**
@@ -6732,12 +6735,13 @@ SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
 /**
  * sys_sched_setparam - set/change the DEADLINE parameters of a thread
  * @pid: the pid in question.
+ * @len: size of data pointed by param_ex.
  * @param_ex: structure containing the new parameters (deadline, runtime, etc.).
  */
-SYSCALL_DEFINE2(sched_setparam_ex, pid_t, pid,
+SYSCALL_DEFINE3(sched_setparam_ex, pid_t, pid, unsigned, len,
 		struct sched_param_ex __user *, param_ex)
 {
-	return do_sched_setscheduler_ex(pid, -1, param_ex);
+	return do_sched_setscheduler_ex(pid, -1, len, param_ex);
 }
 
 /**
@@ -6807,9 +6811,10 @@ out_unlock:
 /**
  * sys_sched_getparam - get the DEADLINE task parameters of a thread
  * @pid: the pid in question.
+ * @len: size of data pointed by param_ex.
  * @param_ex: structure containing the new parameters (deadline, runtime, etc.).
  */
-SYSCALL_DEFINE2(sched_getparam_ex, pid_t, pid,
+SYSCALL_DEFINE3(sched_getparam_ex, pid_t, pid, unsigned, len,
 		struct sched_param_ex __user *, param_ex)
 {
 	struct sched_param_ex lp;
@@ -6818,6 +6823,8 @@ SYSCALL_DEFINE2(sched_getparam_ex, pid_t, pid,
 
 	if (!param_ex || pid < 0)
 		return -EINVAL;
+	if (len < sizeof(struct sched_param_ex))
+		return -EINVAL;
 
 	read_lock(&tasklist_lock);
 	p = find_process_by_pid(pid);
@@ -6837,7 +6844,7 @@ SYSCALL_DEFINE2(sched_getparam_ex, pid_t, pid,
 	/*
 	 * This one might sleep, we cannot do it with a spinlock held ...
 	 */
-	retval = copy_to_user(param_ex, &lp, sizeof(*param_ex)) ? -EFAULT : 0;
+	retval = copy_to_user(param_ex, &lp, len) ? -EFAULT : 0;
 
 	return retval;
 
-- 
1.6.0.4

-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
----------------------------------------------------------------------
Dario Faggioli, ReTiS Lab, Scuola Superiore Sant'Anna, Pisa  (Italy)

http://blog.linux.it/raistlin / raistlin@xxxxxxxxx /
dario.faggioli@xxxxxxxxxx

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