afs: Fix access after dec in put functions

Reference-putting functions should not access the object being put after
decrementing the refcount unless they reduce the refcount to zero.

Fix a couple of instances of this in afs by copying the information to be
logged by tracepoint to local variables before doing the decrement.

[Fixed a bit in afs_put_server() that I'd missed but Marc caught]

Fixes: 341f741f04be ("afs: Refcount the afs_call struct")
Fixes: 452181936931 ("afs: Trace afs_server usage")
Fixes: 977e5f8ed0ab ("afs: Split the usage count on struct afs_server")
Signed-off-by: David Howells <>
cc: Marc Dionne <>
Link: # v1
4 files changed