[PATCH 5.4 29/90] soc: ti: wkup_m3_ipc: Fix race condition with rproc_boot

Greg Kroah-Hartman
2020-02-03T16:41:35Z

From: Dave Gerlach <d-gerlach@ti.com>

[ Upstream commit 03729cfa0d543bc996bf959e762ec999afc8f3d2 ]

Any user of wkup_m3_ipc calls wkup_m3_ipc_get to get a handle and this
checks the value of the static variable m3_ipc_state to see if the
wkup_m3 is ready. Currently this is populated during probe before
rproc_boot has been called, meaning there is a window of time that
wkup_m3_ipc_get can return a valid handle but the wkup_m3 itself is not
ready, leading to invalid IPC calls to the wkup_m3 and system
instability.

To avoid this, move the population of the m3_ipc_state variable until
after rproc_boot has succeeded to guarantee a valid and usable handle
is always returned.

Reported-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/soc/ti/wkup_m3_ipc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/ti/wkup_m3_ipc.c b/drivers/soc/ti/wkup_m3_ipc.c
index 378369d9364ae..e9ece45d7a333 100644
--- a/drivers/soc/ti/wkup_m3_ipc.c
+++ b/drivers/soc/ti/wkup_m3_ipc.c
@@ -419,6 +419,8 @@ static void wkup_m3_rproc_boot_thread(struct wkup_m3_ipc *m3_ipc)
ret = rproc_boot(m3_ipc->rproc);
if (ret)
dev_err(dev, "rproc_boot failed\n");
+ else
+ m3_ipc_state = m3_ipc;

do_exit(0);
}
@@ -505,8 +507,6 @@ static int wkup_m3_ipc_probe(struct platform_device *pdev)
goto err_put_rproc;
}

- m3_ipc_state = m3_ipc;
-
return 0;

err_put_rproc:
--
2.20.1