uprobes: Kill uprobe->copy_mutex

Now that ->register_rwsem is safe under ->mmap_sem we can kill
->copy_mutex and abuse down_write(&uprobe->consumer_rwsem).

This makes prepare_uprobe() even more ugly, but we should kill
it anyway.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

1 files changed, 3 insertions, 4 deletions

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 7ec2eb278634..40ced98b2bc8 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -91,7 +91,6 @@ struct uprobe {
         atomic_t                ref;
         struct rw_semaphore     register_rwsem;
         struct rw_semaphore     consumer_rwsem;
-        struct mutex            copy_mutex;     /* TODO: kill me and UPROBE_COPY_INSN */
         struct list_head        pending_list;
         struct uprobe_consumer  *consumers;
         struct inode            *inode;         /* Also hold a ref to inode */
@@ -450,7 +449,6 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset)
         uprobe->offset = offset;
         init_rwsem(&uprobe->register_rwsem);
         init_rwsem(&uprobe->consumer_rwsem);
-        mutex_init(&uprobe->copy_mutex);
         /* For now assume that the instruction need not be single-stepped */
         __set_bit(UPROBE_SKIP_SSTEP, &uprobe->flags);
 
@@ -578,7 +576,8 @@ static int prepare_uprobe(struct uprobe *uprobe, struct file *file,
         if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
                 return ret;
 
-        mutex_lock(&uprobe->copy_mutex);
+        /* TODO: move this into _register, until then we abuse this sem. */
+        down_write(&uprobe->consumer_rwsem);
         if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
                 goto out;
 
@@ -602,7 +601,7 @@ static int prepare_uprobe(struct uprobe *uprobe, struct file *file,
         set_bit(UPROBE_COPY_INSN, &uprobe->flags);
 
  out:
-        mutex_unlock(&uprobe->copy_mutex);
+        up_write(&uprobe->consumer_rwsem);
 
         return ret;
 }