Commit acc080d1 authored Oct 27, 2020 by David Howells

afs: Fix tracing deref-before-check



The patch dca54a7b: "afs: Add tracing for cell refcount and active user
count" from Oct 13, 2020, leads to the following Smatch complaint:

    fs/afs/cell.c:596 afs_unuse_cell()
    warn: variable dereferenced before check 'cell' (see line 592)

Fix this by moving the retrieval of the cell debug ID to after the check of
the validity of the cell pointer.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: dca54a7b ("afs: Add tracing for cell refcount and active user count")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Dan Carpenter <dan.carpenter@oracle.com>

parent 06a17bbe

fs/afs/cell.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -589,7 +589,7 @@ struct afs_cell afs_use_cell(struct afs_cell cell, enum afs_cell_trace reason)
		*/
		void afs_unuse_cell(struct afs_net net, struct afs_cell cell, enum afs_cell_trace reason)
		{
		unsigned int debug_id = cell->debug_id;
		unsigned int debug_id;
		time64_t now, expire_delay;
		int u, a;

		@@ -604,6 +604,7 @@ void afs_unuse_cell(struct afs_net net, struct afs_cell cell, enum afs_cell_tr
		if (cell->vl_servers->nr_servers)
		expire_delay = afs_cell_gc_delay;

		debug_id = cell->debug_id;
		u = atomic_read(&cell->ref);
		a = atomic_dec_return(&cell->active);
		trace_afs_cell(debug_id, u, a, reason);

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