manawyrm has uploaded this change for review.
drivers/dahdi/icE1usb: defer USB transfer when setting loopback mode
The icE1usb driver would deadlock/hang the kernel when trying to configure
a internal loopback mode via the "dahdi_maint" utility.
Previously, it tried to do a USB transfer without enabled interrupts
inside a spinlock, which caused the infinite hang.
This change moves the ice1usb_tx_config() call to a workqueue.
Change-Id: Iba99fc5261059c77cc89d867b21c70a34c9b4ea6
---
M drivers/dahdi/icE1usb/icE1usb.c
1 file changed, 26 insertions(+), 5 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/dahdi-linux refs/changes/42/43642/1
diff --git a/drivers/dahdi/icE1usb/icE1usb.c b/drivers/dahdi/icE1usb/icE1usb.c
index a861515..ebeaee6 100644
--- a/drivers/dahdi/icE1usb/icE1usb.c
+++ b/drivers/dahdi/icE1usb/icE1usb.c
@@ -29,6 +29,7 @@
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
+#include <linux/workqueue.h>
#include <linux/pm_runtime.h>
#include <dahdi/kernel.h>
@@ -135,6 +136,8 @@
} dahdi;
/* is the device still present (true) or already absent/unplugged (false) */
bool present;
+ /* deferred ice1usb_tx_config(), scheduled from the atomic .maint callback */
+ struct work_struct tx_config_work;
/* spinlock protecting concurrent access to fc, {read,write}chunk_idx, ... */
spinlock_t lock;
/* maximum number of 32-byte E1 frames to send in one ISO OUT packet */
@@ -880,11 +883,26 @@
return 0;
}
-/* set some maintenance mode according to 'cmd' */
+static void ice1usb_deferred_tx_config(struct work_struct *work)
+{
+ struct ice1usb *ieu = container_of(work, struct ice1usb, tx_config_work);
+ int rc;
+
+ if (!ieu->present)
+ return;
+
+ rc = ice1usb_tx_config(ieu);
+ if (rc < 0)
+ ieu_err(ieu, "Failed to apply maint TX config: %d\n", rc);
+}
+
+/* set some maintenance mode according to 'cmd'
+ *
+ * Called by the DAHDI core with span->lock held and IRQs disabled, so the
+ * blocking USB I/O is deferred to ice1usb_deferred_tx_config(). */
static int e1u_d_maint(struct dahdi_span *span, int cmd)
{
struct ice1usb *ieu = container_of(span, struct ice1usb, dahdi.span);
- int rc = 0;
ieu_dbg(ieu, "entering %s(%d)", __FUNCTION__, cmd);
@@ -892,12 +910,12 @@
case DAHDI_MAINT_NONE:
ieu_info(ieu, "Clearing all maint modes\n");
ieu->cfg.tx.ext_loopback = ICE1USB_TX_EXT_LOOPBACK_OFF;
- rc = ice1usb_tx_config(ieu);
+ schedule_work(&ieu->tx_config_work);
break;
case DAHDI_MAINT_NETWORKLINELOOP:
ieu_info(ieu, "Turning on network line loopback\n");
ieu->cfg.tx.ext_loopback = ICE1USB_TX_EXT_LOOPBACK_SAME;
- rc = ice1usb_tx_config(ieu);
+ schedule_work(&ieu->tx_config_work);
break;
/* TODO: DAHDI_MAINT_*_DEFECT */
/* TODO: DAHDI_MAINT_ALARM_SIM */
@@ -910,7 +928,7 @@
return -ENOSYS;
}
- return rc;
+ return 0;
}
static const struct dahdi_span_ops ice1usb_span_ops = {
@@ -1413,6 +1431,7 @@
ieu->fc.r_sw = 8192;
ieu->present = true;
spin_lock_init(&ieu->lock);
+ INIT_WORK(&ieu->tx_config_work, ice1usb_deferred_tx_config);
/* locate ON / OFF altsettings */
ieu->alt_off = find_altsetting_off(ieu->usb_intf);
@@ -1514,6 +1533,8 @@
/* will in turn call e1u_d_shutdown() which stops all transfers */
dahdi_unregister_device(ieu->dahdi.dev);
+ cancel_work_sync(&ieu->tx_config_work);
+
ice1usb_free(ieu);
}
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