wimax/i2400m: clarify and fix i2400m->{ready,updown}
The i2400m driver uses two different bits to distinguish how much the
driver is up. i2400m->ready is used to denote that the infrastructure
to communicate with the device is up and running. i2400m->updown is
used to indicate if 'ready' and the device is up and running, ready to
take control and data traffic.
However, all this was pretty dirty and not clear, with many open spots
where race conditions were present.
This commit cleans up the situation by:
- documenting the usage of both bits
- setting them only in specific, well controlled places
(i2400m_dev_start, i2400m_dev_stop)
- ensuring the i2400m workqueue can't get in the middle of the
setting by flushing it when i2400m->ready is set to zero. This
allows the report hook not having to check again for the bit to be
set [rx.c:i2400m_report_hook_work()].
- using i2400m->updown to determine if the device is up and running
instead of the wimax state in i2400m_dev_reset_handle().
- not loosing missed messages sent by the hardware before
i2400m->ready is set. In rx.c, whatever the device sends can be
sent to user space over the message pipes as soon as the wimax
device is registered, so don't wait for i2400m->ready to be set.
Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
diff --git a/drivers/net/wimax/i2400m/driver.c b/drivers/net/wimax/i2400m/driver.c
index a0ae199..6280646 100644
--- a/drivers/net/wimax/i2400m/driver.c
+++ b/drivers/net/wimax/i2400m/driver.c
@@ -455,6 +455,8 @@
result = i2400m->bus_dev_start(i2400m);
if (result < 0)
goto error_bus_dev_start;
+ i2400m->ready = 1;
+ wmb(); /* see i2400m->ready's documentation */
result = i2400m_firmware_check(i2400m); /* fw versions ok? */
if (result < 0)
goto error_fw_check;
@@ -462,7 +464,6 @@
result = i2400m_check_mac_addr(i2400m);
if (result < 0)
goto error_check_mac_addr;
- i2400m->ready = 1;
wimax_state_change(wimax_dev, WIMAX_ST_UNINITIALIZED);
result = i2400m_dev_initialize(i2400m);
if (result < 0)
@@ -475,6 +476,9 @@
error_dev_initialize:
error_check_mac_addr:
+ i2400m->ready = 0;
+ wmb(); /* see i2400m->ready's documentation */
+ flush_workqueue(i2400m->work_queue);
error_fw_check:
i2400m->bus_dev_stop(i2400m);
error_bus_dev_start:
@@ -498,11 +502,15 @@
static
int i2400m_dev_start(struct i2400m *i2400m, enum i2400m_bri bm_flags)
{
- int result;
+ int result = 0;
mutex_lock(&i2400m->init_mutex); /* Well, start the device */
- result = __i2400m_dev_start(i2400m, bm_flags);
- if (result >= 0)
- i2400m->updown = 1;
+ if (i2400m->updown == 0) {
+ result = __i2400m_dev_start(i2400m, bm_flags);
+ if (result >= 0) {
+ i2400m->updown = 1;
+ wmb(); /* see i2400m->updown's documentation */
+ }
+ }
mutex_unlock(&i2400m->init_mutex);
return result;
}
@@ -529,7 +537,14 @@
wimax_state_change(wimax_dev, __WIMAX_ST_QUIESCING);
i2400m_net_wake_stop(i2400m);
i2400m_dev_shutdown(i2400m);
- i2400m->ready = 0;
+ /*
+ * Make sure no report hooks are running *before* we stop the
+ * communication infrastructure with the device.
+ */
+ i2400m->ready = 0; /* nobody can queue work anymore */
+ wmb(); /* see i2400m->ready's documentation */
+ flush_workqueue(i2400m->work_queue);
+
i2400m->bus_dev_stop(i2400m);
destroy_workqueue(i2400m->work_queue);
i2400m_rx_release(i2400m);
@@ -551,6 +566,7 @@
if (i2400m->updown) {
__i2400m_dev_stop(i2400m);
i2400m->updown = 0;
+ wmb(); /* see i2400m->updown's documentation */
}
mutex_unlock(&i2400m->init_mutex);
}
@@ -632,7 +648,6 @@
const char *reason;
struct i2400m *i2400m = iw->i2400m;
struct device *dev = i2400m_dev(i2400m);
- enum wimax_st wimax_state;
struct i2400m_reset_ctx *ctx = i2400m->reset_ctx;
if (WARN_ON(iw->pl_size != sizeof(reason)))
@@ -647,29 +662,28 @@
/* We are still in i2400m_dev_start() [let it fail] or
* i2400m_dev_stop() [we are shutting down anyway, so
* ignore it] or we are resetting somewhere else. */
- dev_err(dev, "device rebooted\n");
+ dev_err(dev, "device rebooted somewhere else?\n");
i2400m_msg_to_dev_cancel_wait(i2400m, -EL3RST);
complete(&i2400m->msg_completion);
goto out;
}
- wimax_state = wimax_state_get(&i2400m->wimax_dev);
- if (wimax_state < WIMAX_ST_UNINITIALIZED) {
- dev_info(dev, "%s: it is down, ignoring\n", reason);
- goto out_unlock; /* ifconfig up/down wasn't called */
+ if (i2400m->updown == 0) {
+ dev_info(dev, "%s: device is down, doing nothing\n", reason);
+ goto out_unlock;
}
dev_err(dev, "%s: reinitializing driver\n", reason);
__i2400m_dev_stop(i2400m);
- i2400m->updown = 0;
result = __i2400m_dev_start(i2400m,
I2400M_BRI_SOFT | I2400M_BRI_MAC_REINIT);
if (result < 0) {
+ i2400m->updown = 0;
+ 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;
- } else
- i2400m->updown = 1;
+ }
out_unlock:
if (i2400m->reset_ctx) {
ctx->result = result;
diff --git a/drivers/net/wimax/i2400m/i2400m.h b/drivers/net/wimax/i2400m/i2400m.h
index 2b9c400..fbc156d 100644
--- a/drivers/net/wimax/i2400m/i2400m.h
+++ b/drivers/net/wimax/i2400m/i2400m.h
@@ -307,6 +307,27 @@
* force this to be the first field so that we can get from
* netdev_priv() the right pointer.
*
+ * @updown: the device is up and ready for transmitting control and
+ * data packets. This implies @ready (communication infrastructure
+ * with the device is ready) and the device's firmware has been
+ * loaded and the device initialized.
+ *
+ * Write to it only inside a i2400m->init_mutex protected area
+ * followed with a wmb(); rmb() before accesing (unless locked
+ * inside i2400m->init_mutex). Read access can be loose like that
+ * [just using rmb()] because the paths that use this also do
+ * other error checks later on.
+ *
+ * @ready: Communication infrastructure with the device is ready, data
+ * frames can start to be passed around (this is lighter than
+ * using the WiMAX state for certain hot paths).
+ *
+ * Write to it only inside a i2400m->init_mutex protected area
+ * followed with a wmb(); rmb() before accesing (unless locked
+ * inside i2400m->init_mutex). Read access can be loose like that
+ * [just using rmb()] because the paths that use this also do
+ * other error checks later on.
+ *
* @rx_reorder: 1 if RX reordering is enabled; this can only be
* set at probe time.
*
@@ -458,7 +479,7 @@
unsigned updown:1; /* Network device is up or down */
unsigned boot_mode:1; /* is the device in boot mode? */
unsigned sboot:1; /* signed or unsigned fw boot */
- unsigned ready:1; /* all probing steps done */
+ unsigned ready:1; /* Device comm infrastructure ready */
unsigned rx_reorder:1; /* RX reorder is enabled */
u8 trace_msg_from_user; /* echo rx msgs to 'trace' pipe */
/* typed u8 so /sys/kernel/debug/u8 can tweak */
diff --git a/drivers/net/wimax/i2400m/rx.c b/drivers/net/wimax/i2400m/rx.c
index bcd411f..82c200a 100644
--- a/drivers/net/wimax/i2400m/rx.c
+++ b/drivers/net/wimax/i2400m/rx.c
@@ -177,8 +177,7 @@
struct i2400m_work *iw =
container_of(ws, struct i2400m_work, ws);
struct i2400m_report_hook_args *args = (void *) iw->pl;
- if (iw->i2400m->ready)
- i2400m_report_hook(iw->i2400m, args->l3l4_hdr, args->size);
+ i2400m_report_hook(iw->i2400m, args->l3l4_hdr, args->size);
kfree_skb(args->skb_rx);
i2400m_put(iw->i2400m);
kfree(iw);
@@ -305,11 +304,12 @@
.l3l4_hdr = l3l4_hdr,
.size = size
};
- if (unlikely(i2400m->ready == 0)) /* only send if up */
- return;
- skb_get(skb_rx);
- i2400m_queue_work(i2400m, i2400m_report_hook_work,
- GFP_KERNEL, &args, sizeof(args));
+ rmb(); /* see i2400m->ready's documentation */
+ if (likely(i2400m->ready)) { /* only send if up */
+ skb_get(skb_rx);
+ i2400m_queue_work(i2400m, i2400m_report_hook_work,
+ GFP_KERNEL, &args, sizeof(args));
+ }
if (unlikely(i2400m->trace_msg_from_user))
wimax_msg(&i2400m->wimax_dev, "echo",
l3l4_hdr, size, GFP_KERNEL);
@@ -363,8 +363,6 @@
msg_type & I2400M_MT_REPORT_MASK ? "REPORT" : "CMD/SET/GET",
msg_type, size);
d_dump(2, dev, l3l4_hdr, size);
- if (unlikely(i2400m->ready == 0)) /* only send if up */
- return;
result = wimax_msg(wimax_dev, "trace", l3l4_hdr, size, GFP_KERNEL);
if (result < 0)
dev_err(dev, "error sending trace to userspace: %d\n",
diff --git a/drivers/net/wimax/i2400m/usb.c b/drivers/net/wimax/i2400m/usb.c
index 07653de..f4dfb60 100644
--- a/drivers/net/wimax/i2400m/usb.c
+++ b/drivers/net/wimax/i2400m/usb.c
@@ -516,7 +516,10 @@
* So at the end, the three cases require common handling.
*
* If at the time of this call the device's firmware is not loaded,
- * nothing has to be done.
+ * nothing has to be done. Note we can be "loose" about not reading
+ * i2400m->updown under i2400m->init_mutex. If it happens to change
+ * inmediately, other parts of the call flow will fail and effectively
+ * catch it.
*
* If the firmware is loaded, we need to:
*
@@ -555,6 +558,7 @@
#endif
d_fnstart(3, dev, "(iface %p pm_msg %u)\n", iface, pm_msg.event);
+ rmb(); /* see i2400m->updown's documentation */
if (i2400m->updown == 0)
goto no_firmware;
if (i2400m->state == I2400M_SS_DATA_PATH_CONNECTED && is_autosuspend) {
@@ -608,6 +612,7 @@
struct i2400m *i2400m = &i2400mu->i2400m;
d_fnstart(3, dev, "(iface %p)\n", iface);
+ rmb(); /* see i2400m->updown's documentation */
if (i2400m->updown == 0) {
d_printf(1, dev, "fw was down, no resume neeed\n");
goto out;
diff --git a/include/net/wimax.h b/include/net/wimax.h
index 2af7bf8..d69c4a7 100644
--- a/include/net/wimax.h
+++ b/include/net/wimax.h
@@ -195,6 +195,12 @@
* defining the `struct nla_policy` for each message, it has to have
* an array size of WIMAX_GNL_ATTR_MAX+1.
*
+ * The op_*() function pointers will not be called if the wimax_dev is
+ * in a state <= %WIMAX_ST_UNINITIALIZED. The exception is:
+ *
+ * - op_reset: can be called at any time after wimax_dev_add() has
+ * been called.
+ *
* THE PIPE INTERFACE:
*
* This interface is kept intentionally simple. The driver can send
