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wimax/i2400m: fix deadlock: don't do BUS reset under i2400m->init_mutex

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Since the addition of the pre/post reset handlers, it became clear
that we cannot do a I2400M-RT-BUS type reset while holding the
init_mutex, as in the case of USB, it will deadlock when trying to
call i2400m_pre_reset().

Thus, the following changes:

 - clarify the fact that calling bus_reset() w/ I2400M_RT_BUS while
   holding init_mutex is a no-no.

 - i2400m_dev_reset_handle() will do a BUS reset to recover a gone
   device after unlocking init_mutex.

 - in the USB reset implementation, when cold and warm reset fails,
   fallback to QUEUING a usb reset, not executing a USB reset, so it
   happens from another context and does not deadlock.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
This commit is contained in:
Inaky Perez-Gonzalez 2009-10-07 12:34:13 +09:00
parent 5eeae35b9a
commit b9ee95010b
3 changed files with 20 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/net/wimax/i2400m/driver.c
View File

@ -765,9 +765,7 @@ void __i2400m_dev_reset_handle(struct work_struct *ws)
wmb(); /* see i2400m->updown's documentation */
dev_err(dev, "%s: cannot start the device: %d\n",
reason, result);
result = i2400m->bus_reset(i2400m, I2400M_RT_BUS);
if (result >= 0)
result = -ENODEV;
result = -EUCLEAN;
}
out_unlock:
if (i2400m->reset_ctx) {
@ -775,6 +773,12 @@ void __i2400m_dev_reset_handle(struct work_struct *ws)
complete(&ctx->completion);
}
mutex_unlock(&i2400m->init_mutex);
if (result == -EUCLEAN) {
/* ops, need to clean up [w/ init_mutex not held] */
result = i2400m->bus_reset(i2400m, I2400M_RT_BUS);
if (result >= 0)
result = -ENODEV;
}
out:
i2400m_put(i2400m);
kfree(iw);

3
drivers/net/wimax/i2400m/i2400m.h
View File

@ -281,6 +281,9 @@ struct i2400m_barker_db;
* process, so it cannot rely on common infrastructure being laid
* out.
*
* IMPORTANT: don't call reset on RT_BUS with i2400m->init_mutex
* held, as the .pre/.post reset handlers will deadlock.
*
* @bus_bm_retries: [fill] How many times shall a firmware upload /
* device initialization be retried? Different models of the same
* device might need different values, hence it is set by the

14
drivers/net/wimax/i2400m/usb.c
View File

@ -254,7 +254,6 @@ int i2400mu_bus_reset(struct i2400m *i2400m, enum i2400m_reset_type rt)
sizeof(i2400m_COLD_BOOT_BARKER),
i2400mu->endpoint_cfg.reset_cold);
else if (rt == I2400M_RT_BUS) {
do_bus_reset:
result = usb_reset_device(i2400mu->usb_dev);
switch (result) {
case 0:
@ -262,7 +261,7 @@ int i2400mu_bus_reset(struct i2400m *i2400m, enum i2400m_reset_type rt)
case -ENODEV:
case -ENOENT:
case -ESHUTDOWN:
result = rt == I2400M_RT_WARM ? -ENODEV : 0;
result = 0;
break; /* We assume the device is disconnected */
default:
dev_err(dev, "USB reset failed (%d), giving up!\n",
@ -275,10 +274,17 @@ int i2400mu_bus_reset(struct i2400m *i2400m, enum i2400m_reset_type rt)
if (result < 0
&& result != -EINVAL /* device is gone */
&& rt != I2400M_RT_BUS) {
/*
* Things failed -- resort to lower level reset, that
* we queue in another context; the reason for this is
* that the pre and post reset functionality requires
* the i2400m->init_mutex; RT_WARM and RT_COLD can
* come from areas where i2400m->init_mutex is taken.
*/
dev_err(dev, "%s reset failed (%d); trying USB reset\n",
rt == I2400M_RT_WARM ? "warm" : "cold", result);
rt = I2400M_RT_BUS;
goto do_bus_reset;
usb_queue_reset_device(i2400mu->usb_iface);
result = -ENODEV;
}
d_fnend(3, dev, "(i2400m %p rt %u) = %d\n", i2400m, rt, result);
return result;