linux-kernel - [PATCH 11/14] ipc: teach the mm about range locking

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Date:   Mon, 20 May 2019 21:52:39 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     akpm@...ux-foundation.org, willy@...radead.org, mhocko@...nel.org,
        mgorman@...hsingularity.net, jglisse@...hat.com,
        ldufour@...ux.vnet.ibm.com, dave@...olabs.net,
        Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH 11/14] ipc: teach the mm about range locking

Conversion is straightforward, mmap_sem is used within the
the same function context most of the time. No change in
semantics.

Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---
 ipc/shm.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/ipc/shm.c b/ipc/shm.c
index ce1ca9f7c6e9..3666fa71bfc2 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -1418,6 +1418,7 @@ COMPAT_SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, void __user *, uptr)
 long do_shmat(int shmid, char __user *shmaddr, int shmflg,
 	      ulong *raddr, unsigned long shmlba)
 {
+	DEFINE_RANGE_LOCK_FULL(mmrange);
 	struct shmid_kernel *shp;
 	unsigned long addr = (unsigned long)shmaddr;
 	unsigned long size;
@@ -1544,7 +1545,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg,
 	if (err)
 		goto out_fput;
 
-	if (down_write_killable(&current->mm->mmap_sem)) {
+	if (mm_write_lock_killable(current->mm, &mmrange)) {
 		err = -EINTR;
 		goto out_fput;
 	}
@@ -1564,7 +1565,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg,
 	if (IS_ERR_VALUE(addr))
 		err = (long)addr;
 invalid:
-	up_write(&current->mm->mmap_sem);
+	mm_write_unlock(current->mm, &mmrange);
 	if (populate)
 		mm_populate(addr, populate);
 
@@ -1625,6 +1626,7 @@ COMPAT_SYSCALL_DEFINE3(shmat, int, shmid, compat_uptr_t, shmaddr, int, shmflg)
  */
 long ksys_shmdt(char __user *shmaddr)
 {
+	DEFINE_RANGE_LOCK_FULL(mmrange);
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	unsigned long addr = (unsigned long)shmaddr;
@@ -1638,7 +1640,7 @@ long ksys_shmdt(char __user *shmaddr)
 	if (addr & ~PAGE_MASK)
 		return retval;
 
-	if (down_write_killable(&mm->mmap_sem))
+	if (mm_write_lock_killable(mm, &mmrange))
 		return -EINTR;
 
 	/*
@@ -1726,7 +1728,7 @@ long ksys_shmdt(char __user *shmaddr)
 
 #endif
 
-	up_write(&mm->mmap_sem);
+	mm_write_unlock(mm, &mmrange);
 	return retval;
 }
 
-- 
2.16.4