crypto: caam - fix endless loop when DECO acquire fails

In case DECO0 cannot be acquired - i.e. run_descriptor_deco0() fails
with -ENODEV, caam_probe() enters an endless loop:

run_descriptor_deco0
	ret -ENODEV
	-> instantiate_rng
		-ENODEV, overwritten by -EAGAIN
		ret -EAGAIN
		-> caam_probe
			-EAGAIN results in endless loop

It turns out the error path in instantiate_rng() is incorrect,
the checks are done in the wrong order.

Cc: <stable@vger.kernel.org> # 3.13+
Fixes: 1005bccd7a4a6 ("crypto: caam - enable instantiation of all RNG4 state handles")
Reported-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Suggested-by: Auer Lukas <lukas.auer@aisec.fraunhofer.de>
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/crypto/caam/ctrl.c b/drivers/crypto/caam/ctrl.c
index 75d280cb2dc0..e843cf410373 100644
--- a/drivers/crypto/caam/ctrl.c
+++ b/drivers/crypto/caam/ctrl.c
@@ -228,12 +228,16 @@ static int instantiate_rng(struct device *ctrldev, int state_handle_mask,
                  * without any error (HW optimizations for later
                  * CAAM eras), then try again.
                  */
+                if (ret)
+                        break;
+
                 rdsta_val = rd_reg32(&ctrl->r4tst[0].rdsta) & RDSTA_IFMASK;
                 if ((status && status != JRSTA_SSRC_JUMP_HALT_CC) ||
-                    !(rdsta_val & (1 << sh_idx)))
+                    !(rdsta_val & (1 << sh_idx))) {
                         ret = -EAGAIN;
-                if (ret)
                         break;
+                }
+
                 dev_info(ctrldev, "Instantiated RNG4 SH%d\n", sh_idx);
                 /* Clear the contents before recreating the descriptor */
                 memset(desc, 0x00, CAAM_CMD_SZ * 7);