[PATCH RESEND] driver-core: fix modparam async_probe request

From: Luis R. Rodriguez
Date: Fri Jan 15 2016 - 18:43:39 EST


From: "Luis R. Rodriguez" <mcgrof@xxxxxxxx>

Commit f2411da746985 ("driver-core: add driver module
asynchronous probe support") added async probe support,
in two forms:

* in-kernel driver specification annotation
* generic async_probe module parameter (modprobe foo async_probe)

To support the generic kernel parameter parse_args() was
extended via commit ecc8617053e0 ("module: add extra
argument for parse_params() callback") however commit
failed to f2411da746985 failed to add the required argument.

This causes a crash then whenever async_probe generic
module parameter is used. This was overlooked when the
form in which in-kernel async probe support was reworked
a bit... Fix this as originally intended.

Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx (4.2+)
Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxx>
---

Resending and addressing Rusty, the other patch I sent on Dec 19
was addressed to Greg by mistake. Sorry about that.

kernel/module.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 8f051a106676..88100ea77c55 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3402,16 +3402,22 @@ out:
static int unknown_module_param_cb(char *param, char *val, const char *modname,
void *arg)
{
- struct module *mod = arg;
+ struct module *mod;
int ret;

if (strcmp(param, "async_probe") == 0) {
+ mod = arg;
+ if (!mod) {
+ ret = -ENOENT;
+ goto out;
+ }
mod->async_probe_requested = true;
return 0;
}

/* Check for magic 'dyndbg' arg */
ret = ddebug_dyndbg_module_param_cb(param, val, modname);
+out:
if (ret != 0)
pr_warn("%s: unknown parameter '%s' ignored\n", modname, param);
return 0;
@@ -3515,7 +3521,7 @@ static int load_module(struct load_info *info, const char __user *uargs,

/* Module is ready to execute: parsing args may do that. */
after_dashes = parse_args(mod->name, mod->args, mod->kp, mod->num_kp,
- -32768, 32767, NULL,
+ -32768, 32767, mod,
unknown_module_param_cb);
if (IS_ERR(after_dashes)) {
err = PTR_ERR(after_dashes);
--
2.6.2