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-rw-r--r--Documentation/workqueue.txt40
-rw-r--r--drivers/i2c/busses/i2c-i801.c5
-rw-r--r--drivers/i2c/busses/i2c-parport.c27
-rw-r--r--include/linux/pci_ids.h4
-rw-r--r--kernel/workqueue.c8
-rw-r--r--lib/xz/xz_dec_lzma2.c6
6 files changed, 69 insertions, 21 deletions
diff --git a/Documentation/workqueue.txt b/Documentation/workqueue.txt
index 01c513fac40..a0b577de918 100644
--- a/Documentation/workqueue.txt
+++ b/Documentation/workqueue.txt
@@ -12,6 +12,7 @@ CONTENTS
4. Application Programming Interface (API)
5. Example Execution Scenarios
6. Guidelines
+7. Debugging
1. Introduction
@@ -379,3 +380,42 @@ If q1 has WQ_CPU_INTENSIVE set,
* Unless work items are expected to consume a huge amount of CPU
cycles, using a bound wq is usually beneficial due to the increased
level of locality in wq operations and work item execution.
+
+
+7. Debugging
+
+Because the work functions are executed by generic worker threads
+there are a few tricks needed to shed some light on misbehaving
+workqueue users.
+
+Worker threads show up in the process list as:
+
+root 5671 0.0 0.0 0 0 ? S 12:07 0:00 [kworker/0:1]
+root 5672 0.0 0.0 0 0 ? S 12:07 0:00 [kworker/1:2]
+root 5673 0.0 0.0 0 0 ? S 12:12 0:00 [kworker/0:0]
+root 5674 0.0 0.0 0 0 ? S 12:13 0:00 [kworker/1:0]
+
+If kworkers are going crazy (using too much cpu), there are two types
+of possible problems:
+
+ 1. Something beeing scheduled in rapid succession
+ 2. A single work item that consumes lots of cpu cycles
+
+The first one can be tracked using tracing:
+
+ $ echo workqueue:workqueue_queue_work > /sys/kernel/debug/tracing/set_event
+ $ cat /sys/kernel/debug/tracing/trace_pipe > out.txt
+ (wait a few secs)
+ ^C
+
+If something is busy looping on work queueing, it would be dominating
+the output and the offender can be determined with the work item
+function.
+
+For the second type of problems it should be possible to just check
+the stack trace of the offending worker thread.
+
+ $ cat /proc/THE_OFFENDING_KWORKER/stack
+
+The work item's function should be trivially visible in the stack
+trace.
diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 72c0415f6f9..455e909bc76 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -134,10 +134,15 @@
SMBHSTSTS_BUS_ERR | SMBHSTSTS_DEV_ERR | \
SMBHSTSTS_INTR)
+/* Older devices have their ID defined in <linux/pci_ids.h> */
+#define PCI_DEVICE_ID_INTEL_COUGARPOINT_SMBUS 0x1c22
+#define PCI_DEVICE_ID_INTEL_PATSBURG_SMBUS 0x1d22
/* Patsburg also has three 'Integrated Device Function' SMBus controllers */
#define PCI_DEVICE_ID_INTEL_PATSBURG_SMBUS_IDF0 0x1d70
#define PCI_DEVICE_ID_INTEL_PATSBURG_SMBUS_IDF1 0x1d71
#define PCI_DEVICE_ID_INTEL_PATSBURG_SMBUS_IDF2 0x1d72
+#define PCI_DEVICE_ID_INTEL_DH89XXCC_SMBUS 0x2330
+#define PCI_DEVICE_ID_INTEL_5_3400_SERIES_SMBUS 0x3b30
struct i801_priv {
struct i2c_adapter adapter;
diff --git a/drivers/i2c/busses/i2c-parport.c b/drivers/i2c/busses/i2c-parport.c
index 0eb1515541e..2dbba163b10 100644
--- a/drivers/i2c/busses/i2c-parport.c
+++ b/drivers/i2c/busses/i2c-parport.c
@@ -1,7 +1,7 @@
/* ------------------------------------------------------------------------ *
* i2c-parport.c I2C bus over parallel port *
* ------------------------------------------------------------------------ *
- Copyright (C) 2003-2010 Jean Delvare <khali@linux-fr.org>
+ Copyright (C) 2003-2011 Jean Delvare <khali@linux-fr.org>
Based on older i2c-philips-par.c driver
Copyright (C) 1995-2000 Simon G. Vogl
@@ -33,6 +33,8 @@
#include <linux/i2c-algo-bit.h>
#include <linux/i2c-smbus.h>
#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
#include "i2c-parport.h"
/* ----- Device list ------------------------------------------------------ */
@@ -43,10 +45,11 @@ struct i2c_par {
struct i2c_algo_bit_data algo_data;
struct i2c_smbus_alert_setup alert_data;
struct i2c_client *ara;
- struct i2c_par *next;
+ struct list_head node;
};
-static struct i2c_par *adapter_list;
+static LIST_HEAD(adapter_list);
+static DEFINE_MUTEX(adapter_list_lock);
/* ----- Low-level parallel port access ----------------------------------- */
@@ -228,8 +231,9 @@ static void i2c_parport_attach (struct parport *port)
}
/* Add the new adapter to the list */
- adapter->next = adapter_list;
- adapter_list = adapter;
+ mutex_lock(&adapter_list_lock);
+ list_add_tail(&adapter->node, &adapter_list);
+ mutex_unlock(&adapter_list_lock);
return;
ERROR1:
@@ -241,11 +245,11 @@ ERROR0:
static void i2c_parport_detach (struct parport *port)
{
- struct i2c_par *adapter, *prev;
+ struct i2c_par *adapter, *_n;
/* Walk the list */
- for (prev = NULL, adapter = adapter_list; adapter;
- prev = adapter, adapter = adapter->next) {
+ mutex_lock(&adapter_list_lock);
+ list_for_each_entry_safe(adapter, _n, &adapter_list, node) {
if (adapter->pdev->port == port) {
if (adapter->ara) {
parport_disable_irq(port);
@@ -259,14 +263,11 @@ static void i2c_parport_detach (struct parport *port)
parport_release(adapter->pdev);
parport_unregister_device(adapter->pdev);
- if (prev)
- prev->next = adapter->next;
- else
- adapter_list = adapter->next;
+ list_del(&adapter->node);
kfree(adapter);
- return;
}
}
+ mutex_unlock(&adapter_list_lock);
}
static struct parport_driver i2c_parport_driver = {
diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
index 4e2c9150a78..8abe8d78c4b 100644
--- a/include/linux/pci_ids.h
+++ b/include/linux/pci_ids.h
@@ -2477,15 +2477,12 @@
#define PCI_DEVICE_ID_INTEL_82840_HB 0x1a21
#define PCI_DEVICE_ID_INTEL_82845_HB 0x1a30
#define PCI_DEVICE_ID_INTEL_IOAT 0x1a38
-#define PCI_DEVICE_ID_INTEL_COUGARPOINT_SMBUS 0x1c22
#define PCI_DEVICE_ID_INTEL_COUGARPOINT_LPC_MIN 0x1c41
#define PCI_DEVICE_ID_INTEL_COUGARPOINT_LPC_MAX 0x1c5f
-#define PCI_DEVICE_ID_INTEL_PATSBURG_SMBUS 0x1d22
#define PCI_DEVICE_ID_INTEL_PATSBURG_LPC_0 0x1d40
#define PCI_DEVICE_ID_INTEL_PATSBURG_LPC_1 0x1d41
#define PCI_DEVICE_ID_INTEL_DH89XXCC_LPC_MIN 0x2310
#define PCI_DEVICE_ID_INTEL_DH89XXCC_LPC_MAX 0x231f
-#define PCI_DEVICE_ID_INTEL_DH89XXCC_SMBUS 0x2330
#define PCI_DEVICE_ID_INTEL_82801AA_0 0x2410
#define PCI_DEVICE_ID_INTEL_82801AA_1 0x2411
#define PCI_DEVICE_ID_INTEL_82801AA_3 0x2413
@@ -2696,7 +2693,6 @@
#define PCI_DEVICE_ID_INTEL_ICH10_5 0x3a60
#define PCI_DEVICE_ID_INTEL_5_3400_SERIES_LPC_MIN 0x3b00
#define PCI_DEVICE_ID_INTEL_5_3400_SERIES_LPC_MAX 0x3b1f
-#define PCI_DEVICE_ID_INTEL_5_3400_SERIES_SMBUS 0x3b30
#define PCI_DEVICE_ID_INTEL_IOAT_SNB 0x402f
#define PCI_DEVICE_ID_INTEL_5100_16 0x65f0
#define PCI_DEVICE_ID_INTEL_5100_21 0x65f5
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 8859a41806d..e3378e8d3a5 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1291,8 +1291,14 @@ __acquires(&gcwq->lock)
return true;
spin_unlock_irq(&gcwq->lock);
- /* CPU has come up in between, retry migration */
+ /*
+ * We've raced with CPU hot[un]plug. Give it a breather
+ * and retry migration. cond_resched() is required here;
+ * otherwise, we might deadlock against cpu_stop trying to
+ * bring down the CPU on non-preemptive kernel.
+ */
cpu_relax();
+ cond_resched();
}
}
diff --git a/lib/xz/xz_dec_lzma2.c b/lib/xz/xz_dec_lzma2.c
index ea5fa4fe9d6..a6cdc969ea4 100644
--- a/lib/xz/xz_dec_lzma2.c
+++ b/lib/xz/xz_dec_lzma2.c
@@ -969,6 +969,9 @@ XZ_EXTERN enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s,
*/
tmp = b->in[b->in_pos++];
+ if (tmp == 0x00)
+ return XZ_STREAM_END;
+
if (tmp >= 0xE0 || tmp == 0x01) {
s->lzma2.need_props = true;
s->lzma2.need_dict_reset = false;
@@ -1001,9 +1004,6 @@ XZ_EXTERN enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s,
lzma_reset(s);
}
} else {
- if (tmp == 0x00)
- return XZ_STREAM_END;
-
if (tmp > 0x02)
return XZ_DATA_ERROR;
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-16 08:22:27 +0000