mm: return EBADF if pidfd is invalid

This patch makes returning of EBADF when the fd passed as argument is
invalid. The implementaion relies on pidfd_get_pid's error return.

This patch also fixes syscall declare part since we removed pid support.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Minchan Kim <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Christian Brauner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Stephen Rothwell <[email protected]>

include/linux/compat.h

@@ -827,10 +827,10 @@ asmlinkage long compat_sys_pwritev64v2(unsigned long fd,
 		unsigned long vlen, loff_t pos, rwf_t flags);
 #endif
 
-asmlinkage ssize_t compat_sys_process_madvise(compat_int_t which,
-		compat_pid_t upid, const struct compat_iovec __user *vec,
+asmlinkage ssize_t compat_sys_process_madvise(compat_int_t pidfd,
+		const struct compat_iovec __user *vec,
 		compat_ulong_t vlen, compat_int_t behavior,
-		compat_ulong_t flags);
+		compat_int_t flags);
 
 /*
  * Deprecated system calls which are still defined in

include/linux/syscalls.h

@@ -879,9 +879,8 @@ asmlinkage long sys_munlockall(void);
 asmlinkage long sys_mincore(unsigned long start, size_t len,
 				unsigned char __user * vec);
 asmlinkage long sys_madvise(unsigned long start, size_t len, int behavior);
-asmlinkage long sys_process_madvise(int which, pid_t upid,
-		const struct iovec __user *vec, unsigned long vlen,
-		int behavior, unsigned long flags);
+asmlinkage long sys_process_madvise(int pidfd, const struct iovec __user *vec,
+		unsigned long vlen, int behavior, unsigned int flags);
 asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
 			unsigned long prot, unsigned long pgoff,
 			unsigned long flags);

mm/madvise.c

@@ -1242,9 +1242,6 @@ static ssize_t do_process_madvise(int pidfd, struct iov_iter *iter,
 	if (flags != 0)
 		return -EINVAL;
 
-	if (pidfd < 0)
-		return -EINVAL;
-
 	pid = pidfd_get_pid(pidfd);
 	if (IS_ERR(pid))
 		return PTR_ERR(pid);