From b9ee95010bee6c0e17d18bc9d9c0cfab6e8cb73a Mon Sep 17 00:00:00 2001 From: Inaky Perez-Gonzalez Date: Wed, 7 Oct 2009 12:34:13 +0900 Subject: [PATCH] wimax/i2400m: fix deadlock: don't do BUS reset under i2400m->init_mutex 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 --- drivers/net/wimax/i2400m/driver.c | 10 +++++++--- drivers/net/wimax/i2400m/i2400m.h | 3 +++ drivers/net/wimax/i2400m/usb.c | 14 ++++++++++---- 3 files changed, 20 insertions(+), 7 deletions(-) diff --git a/drivers/net/wimax/i2400m/driver.c b/drivers/net/wimax/i2400m/driver.c index 810eda7dbdba..10673af5a7f0 100644 --- a/drivers/net/wimax/i2400m/driver.c +++ b/drivers/net/wimax/i2400m/driver.c @@ -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 @@ out_unlock: 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); diff --git a/drivers/net/wimax/i2400m/i2400m.h b/drivers/net/wimax/i2400m/i2400m.h index 8fc8a0ca5126..f5ed7d5cee47 100644 --- a/drivers/net/wimax/i2400m/i2400m.h +++ b/drivers/net/wimax/i2400m/i2400m.h @@ -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 diff --git a/drivers/net/wimax/i2400m/usb.c b/drivers/net/wimax/i2400m/usb.c index 8b246cc498b1..418db12b0cd7 100644 --- a/drivers/net/wimax/i2400m/usb.c +++ b/drivers/net/wimax/i2400m/usb.c @@ -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 @@ do_bus_reset: 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 @@ do_bus_reset: 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; -- 2.34.1