Date:	Fri, 14 May 2010 19:19:22 -0700
From:	mgross <markgross@...gnar.org>
To:	rjw@...k.pl, Valdis.Kletnieks@...eu, mgross@...ux.intel.com
Cc:	akpm@...ux-foundation.org, davem@...emloft.net,
	linux-kernel@...r.kernel.org, e1000-devel@...ts.sourceforge.net,
	netdev@...r.kernel.org, linux-pm@...ts.linux-foundation.org
Subject: [patch] pm_qos update fixing mmotm 2010-05-11 -dies in
 pm_qos_update_request()

I apologize for the goofy email address.  

The following is a fix for the crash reported by Valdis.

The problem was that the original pm_qos silently fails when a request
update is passed to a parameter that has not been added to the list
yet.  It seems that the e1000e is doing this.  This update restores this
behavior.

I need to think about how to better handle such abuse, but for now this
restores the original behavior.

Signed-off-by: markgross <markgross@...gnar.org>
--mgross


>From 66700dc26ab7582bc7351541ba2e6241cc4b4144 Mon Sep 17 00:00:00 2001
From: mgross <mgross@...oss-desktop.(none)>
Date: Fri, 14 May 2010 19:05:44 -0700
Subject: [PATCH] PM QOS update
 This patch changes the string based list management to a handle base
 implementation to help with the hot path use of pm-qos, it also renames
 much of the API to use "request" as opposed to "requirement" that was
 used in the initial implementation.  I did this because request more
 accurately represents what it actually does.

Also, I added a string based ABI for users wanting to use a string
interface.  So if the user writes 0xDDDDDDDD formatted hex it will be
accepted by the interface.  (someone asked me for it and I don't think
it hurts anything.)

This patch updates some documentation input I got from Randy.

This version handles a use case where pm_qos update requests need to
silently not fail if the update is being sent to a handle that is null.
This is what happened in the initial version of pm-qos if you used a
string that wasn't in the list.

Signed-off-by: markgross <mgross@...ux.intel.com>
---
 Documentation/power/pm_qos_interface.txt |   48 ++++---
 drivers/acpi/processor_idle.c            |    2 +-
 drivers/cpuidle/governors/ladder.c       |    2 +-
 drivers/cpuidle/governors/menu.c         |    2 +-
 drivers/net/e1000e/netdev.c              |   22 ++--
 drivers/net/igbvf/netdev.c               |    6 +-
 drivers/net/wireless/ipw2x00/ipw2100.c   |   11 +-
 include/linux/netdevice.h                |    4 +
 include/linux/pm_qos_params.h            |   14 +-
 include/sound/pcm.h                      |    3 +-
 kernel/pm_qos_params.c                   |  217 +++++++++++++++---------------
 net/mac80211/mlme.c                      |    2 +-
 sound/core/pcm.c                         |    3 -
 sound/core/pcm_native.c                  |   14 +-
 14 files changed, 179 insertions(+), 171 deletions(-)

diff --git a/Documentation/power/pm_qos_interface.txt b/Documentation/power/pm_qos_interface.txt
index c40866e..bfed898 100644
--- a/Documentation/power/pm_qos_interface.txt
+++ b/Documentation/power/pm_qos_interface.txt
@@ -18,44 +18,46 @@ and pm_qos_params.h.  This is done because having the available parameters
 being runtime configurable or changeable from a driver was seen as too easy to
 abuse.
 
-For each parameter a list of performance requirements is maintained along with
+For each parameter a list of performance requests is maintained along with
 an aggregated target value.  The aggregated target value is updated with
-changes to the requirement list or elements of the list.  Typically the
-aggregated target value is simply the max or min of the requirement values held
+changes to the request list or elements of the list.  Typically the
+aggregated target value is simply the max or min of the request values held
 in the parameter list elements.
 
 From kernel mode the use of this interface is simple:
-pm_qos_add_requirement(param_id, name, target_value):
-Will insert a named element in the list for that identified PM_QOS parameter
-with the target value.  Upon change to this list the new target is recomputed
-and any registered notifiers are called only if the target value is now
-different.
 
-pm_qos_update_requirement(param_id, name, new_target_value):
-Will search the list identified by the param_id for the named list element and
-then update its target value, calling the notification tree if the aggregated
-target is changed.  with that name is already registered.
+handle = pm_qos_add_request(param_class, target_value):
+Will insert an element into the list for that identified PM_QOS class with the
+target value.  Upon change to this list the new target is recomputed and any
+registered notifiers are called only if the target value is now different.
+Clients of pm_qos need to save the returned handle.
 
-pm_qos_remove_requirement(param_id, name):
-Will search the identified list for the named element and remove it, after
-removal it will update the aggregate target and call the notification tree if
-the target was changed as a result of removing the named requirement.
+void pm_qos_update_request(handle, new_target_value):
+Will update the list element pointed to by the handle with the new target value
+and recompute the new aggregated target, calling the notification tree if the
+target is changed.
+
+void pm_qos_remove_request(handle):
+Will remove the element.  After removal it will update the aggregate target and
+call the notification tree if the target was changed as a result of removing
+the request.
 
 
 From user mode:
-Only processes can register a pm_qos requirement.  To provide for automatic
-cleanup for process the interface requires the process to register its
-parameter requirements in the following way:
+Only processes can register a pm_qos request.  To provide for automatic
+cleanup of a process, the interface requires the process to register its
+parameter requests in the following way:
 
 To register the default pm_qos target for the specific parameter, the process
 must open one of /dev/[cpu_dma_latency, network_latency, network_throughput]
 
 As long as the device node is held open that process has a registered
-requirement on the parameter.  The name of the requirement is "process_<PID>"
-derived from the current->pid from within the open system call.
+request on the parameter.
 
-To change the requested target value the process needs to write a s32 value to
-the open device node.  This translates to a pm_qos_update_requirement call.
+To change the requested target value the process needs to write an s32 value to
+the open device node.  Alternatively the user mode program could write a hex
+string for the value using 10 char long format e.g. "0x12345678".  This
+translates to a pm_qos_update_request call.
 
 To remove the user mode request for a target value simply close the device
 node.
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 5939e7f..c3817e1 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -698,7 +698,7 @@ static int acpi_processor_power_seq_show(struct seq_file *seq, void *offset)
 		   "max_cstate:              C%d\n"
 		   "maximum allowed latency: %d usec\n",
 		   pr->power.state ? pr->power.state - pr->power.states : 0,
-		   max_cstate, pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY));
+		   max_cstate, pm_qos_request(PM_QOS_CPU_DMA_LATENCY));
 
 	seq_puts(seq, "states:\n");
 
diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c
index 1c1ceb4..12c9890 100644
--- a/drivers/cpuidle/governors/ladder.c
+++ b/drivers/cpuidle/governors/ladder.c
@@ -67,7 +67,7 @@ static int ladder_select_state(struct cpuidle_device *dev)
 	struct ladder_device *ldev = &__get_cpu_var(ladder_devices);
 	struct ladder_device_state *last_state;
 	int last_residency, last_idx = ldev->last_state_idx;
-	int latency_req = pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY);
+	int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
 
 	/* Special case when user has set very strict latency requirement */
 	if (unlikely(latency_req == 0)) {
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index f8e57c6..b81ad9c 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -182,7 +182,7 @@ static u64 div_round64(u64 dividend, u32 divisor)
 static int menu_select(struct cpuidle_device *dev)
 {
 	struct menu_device *data = &__get_cpu_var(menu_devices);
-	int latency_req = pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY);
+	int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
 	int i;
 	int multiplier;
 
diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
index dbf8178..d5d55c6 100644
--- a/drivers/net/e1000e/netdev.c
+++ b/drivers/net/e1000e/netdev.c
@@ -2524,12 +2524,12 @@ static void e1000_configure_rx(struct e1000_adapter *adapter)
 			 * excessive C-state transition latencies result in
 			 * dropped transactions.
 			 */
-			pm_qos_update_requirement(PM_QOS_CPU_DMA_LATENCY,
-						  adapter->netdev->name, 55);
+			pm_qos_update_request(
+				adapter->netdev->pm_qos_req, 55);
 		} else {
-			pm_qos_update_requirement(PM_QOS_CPU_DMA_LATENCY,
-						  adapter->netdev->name,
-						  PM_QOS_DEFAULT_VALUE);
+			pm_qos_update_request(
+				adapter->netdev->pm_qos_req,
+				PM_QOS_DEFAULT_VALUE);
 		}
 	}
 
@@ -2824,8 +2824,8 @@ int e1000e_up(struct e1000_adapter *adapter)
 
 	/* DMA latency requirement to workaround early-receive/jumbo issue */
 	if (adapter->flags & FLAG_HAS_ERT)
-		pm_qos_add_requirement(PM_QOS_CPU_DMA_LATENCY,
-		                       adapter->netdev->name,
+		adapter->netdev->pm_qos_req =
+			pm_qos_add_request(PM_QOS_CPU_DMA_LATENCY,
 				       PM_QOS_DEFAULT_VALUE);
 
 	/* hardware has been reset, we need to reload some things */
@@ -2887,9 +2887,11 @@ void e1000e_down(struct e1000_adapter *adapter)
 	e1000_clean_tx_ring(adapter);
 	e1000_clean_rx_ring(adapter);
 
-	if (adapter->flags & FLAG_HAS_ERT)
-		pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY,
-		                          adapter->netdev->name);
+	if (adapter->flags & FLAG_HAS_ERT) {
+		pm_qos_remove_request(
+			      adapter->netdev->pm_qos_req);
+		adapter->netdev->pm_qos_req = NULL;
+	}
 
 	/*
 	 * TODO: for power management, we could drop the link and
diff --git a/drivers/net/igbvf/netdev.c b/drivers/net/igbvf/netdev.c
index 1b1edad..f16e981 100644
--- a/drivers/net/igbvf/netdev.c
+++ b/drivers/net/igbvf/netdev.c
@@ -48,6 +48,7 @@
 #define DRV_VERSION "1.0.0-k0"
 char igbvf_driver_name[] = "igbvf";
 const char igbvf_driver_version[] = DRV_VERSION;
+struct pm_qos_request_list *igbvf_driver_pm_qos_req;
 static const char igbvf_driver_string[] =
 				"Intel(R) Virtual Function Network Driver";
 static const char igbvf_copyright[] = "Copyright (c) 2009 Intel Corporation.";
@@ -2899,7 +2900,7 @@ static int __init igbvf_init_module(void)
 	printk(KERN_INFO "%s\n", igbvf_copyright);
 
 	ret = pci_register_driver(&igbvf_driver);
-	pm_qos_add_requirement(PM_QOS_CPU_DMA_LATENCY, igbvf_driver_name,
+	igbvf_driver_pm_qos_req = pm_qos_add_request(PM_QOS_CPU_DMA_LATENCY,
 	                       PM_QOS_DEFAULT_VALUE);
 
 	return ret;
@@ -2915,7 +2916,8 @@ module_init(igbvf_init_module);
 static void __exit igbvf_exit_module(void)
 {
 	pci_unregister_driver(&igbvf_driver);
-	pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY, igbvf_driver_name);
+	pm_qos_remove_request(igbvf_driver_pm_qos_req);
+	igbvf_driver_pm_qos_req = NULL;
 }
 module_exit(igbvf_exit_module);
 
diff --git a/drivers/net/wireless/ipw2x00/ipw2100.c b/drivers/net/wireless/ipw2x00/ipw2100.c
index 9b72c45..2b05fe5 100644
--- a/drivers/net/wireless/ipw2x00/ipw2100.c
+++ b/drivers/net/wireless/ipw2x00/ipw2100.c
@@ -174,6 +174,8 @@ that only one external action is invoked at a time.
 #define DRV_DESCRIPTION	"Intel(R) PRO/Wireless 2100 Network Driver"
 #define DRV_COPYRIGHT	"Copyright(c) 2003-2006 Intel Corporation"
 
+struct pm_qos_request_list *ipw2100_pm_qos_req;
+
 /* Debugging stuff */
 #ifdef CONFIG_IPW2100_DEBUG
 #define IPW2100_RX_DEBUG	/* Reception debugging */
@@ -1739,7 +1741,7 @@ static int ipw2100_up(struct ipw2100_priv *priv, int deferred)
 	/* the ipw2100 hardware really doesn't want power management delays
 	 * longer than 175usec
 	 */
-	pm_qos_update_requirement(PM_QOS_CPU_DMA_LATENCY, "ipw2100", 175);
+	pm_qos_update_request(ipw2100_pm_qos_req, 175);
 
 	/* If the interrupt is enabled, turn it off... */
 	spin_lock_irqsave(&priv->low_lock, flags);
@@ -1887,8 +1889,7 @@ static void ipw2100_down(struct ipw2100_priv *priv)
 	ipw2100_disable_interrupts(priv);
 	spin_unlock_irqrestore(&priv->low_lock, flags);
 
-	pm_qos_update_requirement(PM_QOS_CPU_DMA_LATENCY, "ipw2100",
-			PM_QOS_DEFAULT_VALUE);
+	pm_qos_update_request(ipw2100_pm_qos_req, PM_QOS_DEFAULT_VALUE);
 
 	/* We have to signal any supplicant if we are disassociating */
 	if (associated)
@@ -6669,7 +6670,7 @@ static int __init ipw2100_init(void)
 	if (ret)
 		goto out;
 
-	pm_qos_add_requirement(PM_QOS_CPU_DMA_LATENCY, "ipw2100",
+	ipw2100_pm_qos_req = pm_qos_add_request(PM_QOS_CPU_DMA_LATENCY,
 			PM_QOS_DEFAULT_VALUE);
 #ifdef CONFIG_IPW2100_DEBUG
 	ipw2100_debug_level = debug;
@@ -6692,7 +6693,7 @@ static void __exit ipw2100_exit(void)
 			   &driver_attr_debug_level);
 #endif
 	pci_unregister_driver(&ipw2100_pci_driver);
-	pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY, "ipw2100");
+	pm_qos_remove_request(ipw2100_pm_qos_req);
 }
 
 module_init(ipw2100_init);
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index fa8b476..3857517 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -31,6 +31,7 @@
 #include <linux/if_link.h>
 
 #ifdef __KERNEL__
+#include <linux/pm_qos_params.h>
 #include <linux/timer.h>
 #include <linux/delay.h>
 #include <linux/mm.h>
@@ -711,6 +712,9 @@ struct net_device {
 	 * the interface.
 	 */
 	char			name[IFNAMSIZ];
+
+	struct pm_qos_request_list *pm_qos_req;
+
 	/* device name hash chain */
 	struct hlist_node	name_hlist;
 	/* snmp alias */
diff --git a/include/linux/pm_qos_params.h b/include/linux/pm_qos_params.h
index d74f75e..8ba440e 100644
--- a/include/linux/pm_qos_params.h
+++ b/include/linux/pm_qos_params.h
@@ -14,12 +14,14 @@
 #define PM_QOS_NUM_CLASSES 4
 #define PM_QOS_DEFAULT_VALUE -1
 
-int pm_qos_add_requirement(int qos, char *name, s32 value);
-int pm_qos_update_requirement(int qos, char *name, s32 new_value);
-void pm_qos_remove_requirement(int qos, char *name);
+struct pm_qos_request_list;
 
-int pm_qos_requirement(int qos);
+struct pm_qos_request_list *pm_qos_add_request(int pm_qos_class, s32 value);
+void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req,
+		s32 new_value);
+void pm_qos_remove_request(struct pm_qos_request_list *pm_qos_req);
 
-int pm_qos_add_notifier(int qos, struct notifier_block *notifier);
-int pm_qos_remove_notifier(int qos, struct notifier_block *notifier);
+int pm_qos_request(int pm_qos_class);
+int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier);
+int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier);
 
diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 8b611a5..dd76cde 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -29,6 +29,7 @@
 #include <linux/poll.h>
 #include <linux/mm.h>
 #include <linux/bitops.h>
+#include <linux/pm_qos_params.h>
 
 #define snd_pcm_substream_chip(substream) ((substream)->private_data)
 #define snd_pcm_chip(pcm) ((pcm)->private_data)
@@ -365,7 +366,7 @@ struct snd_pcm_substream {
 	int number;
 	char name[32];			/* substream name */
 	int stream;			/* stream (direction) */
-	char latency_id[20];		/* latency identifier */
+	struct pm_qos_request_list *latency_pm_qos_req; /* pm_qos request */
 	size_t buffer_bytes_max;	/* limit ring buffer size */
 	struct snd_dma_buffer dma_buffer;
 	unsigned int dma_buf_id;
diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
index 3db49b9..dfa1425 100644
--- a/kernel/pm_qos_params.c
+++ b/kernel/pm_qos_params.c
@@ -2,7 +2,7 @@
  * This module exposes the interface to kernel space for specifying
  * QoS dependencies.  It provides infrastructure for registration of:
  *
- * Dependents on a QoS value : register requirements
+ * Dependents on a QoS value : register requests
  * Watchers of QoS value : get notified when target QoS value changes
  *
  * This QoS design is best effort based.  Dependents register their QoS needs.
@@ -14,19 +14,21 @@
  * timeout: usec <-- currently not used.
  * throughput: kbs (kilo byte / sec)
  *
- * There are lists of pm_qos_objects each one wrapping requirements, notifiers
+ * There are lists of pm_qos_objects each one wrapping requests, notifiers
  *
- * User mode requirements on a QOS parameter register themselves to the
+ * User mode requests on a QOS parameter register themselves to the
  * subsystem by opening the device node /dev/... and writing there request to
  * the node.  As long as the process holds a file handle open to the node the
  * client continues to be accounted for.  Upon file release the usermode
- * requirement is removed and a new qos target is computed.  This way when the
- * requirement that the application has is cleaned up when closes the file
+ * request is removed and a new qos target is computed.  This way when the
+ * request that the application has is cleaned up when closes the file
  * pointer or exits the pm_qos_object will get an opportunity to clean up.
  *
  * Mark Gross <mgross@...ux.intel.com>
  */
 
+/*#define DEBUG*/
+
 #include <linux/pm_qos_params.h>
 #include <linux/sched.h>
 #include <linux/spinlock.h>
@@ -42,25 +44,25 @@
 #include <linux/uaccess.h>
 
 /*
- * locking rule: all changes to requirements or notifiers lists
+ * locking rule: all changes to requests or notifiers lists
  * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
  * held, taken with _irqsave.  One lock to rule them all
  */
-struct requirement_list {
+struct pm_qos_request_list {
 	struct list_head list;
 	union {
 		s32 value;
 		s32 usec;
 		s32 kbps;
 	};
-	char *name;
+	int pm_qos_class;
 };
 
 static s32 max_compare(s32 v1, s32 v2);
 static s32 min_compare(s32 v1, s32 v2);
 
 struct pm_qos_object {
-	struct requirement_list requirements;
+	struct pm_qos_request_list requests;
 	struct blocking_notifier_head *notifiers;
 	struct miscdevice pm_qos_power_miscdev;
 	char *name;
@@ -72,7 +74,7 @@ struct pm_qos_object {
 static struct pm_qos_object null_pm_qos;
 static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
 static struct pm_qos_object cpu_dma_pm_qos = {
-	.requirements = {LIST_HEAD_INIT(cpu_dma_pm_qos.requirements.list)},
+	.requests = {LIST_HEAD_INIT(cpu_dma_pm_qos.requests.list)},
 	.notifiers = &cpu_dma_lat_notifier,
 	.name = "cpu_dma_latency",
 	.default_value = 2000 * USEC_PER_SEC,
@@ -82,7 +84,7 @@ static struct pm_qos_object cpu_dma_pm_qos = {
 
 static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
 static struct pm_qos_object network_lat_pm_qos = {
-	.requirements = {LIST_HEAD_INIT(network_lat_pm_qos.requirements.list)},
+	.requests = {LIST_HEAD_INIT(network_lat_pm_qos.requests.list)},
 	.notifiers = &network_lat_notifier,
 	.name = "network_latency",
 	.default_value = 2000 * USEC_PER_SEC,
@@ -93,8 +95,7 @@ static struct pm_qos_object network_lat_pm_qos = {
 
 static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
 static struct pm_qos_object network_throughput_pm_qos = {
-	.requirements =
-		{LIST_HEAD_INIT(network_throughput_pm_qos.requirements.list)},
+	.requests = {LIST_HEAD_INIT(network_throughput_pm_qos.requests.list)},
 	.notifiers = &network_throughput_notifier,
 	.name = "network_throughput",
 	.default_value = 0,
@@ -135,31 +136,34 @@ static s32 min_compare(s32 v1, s32 v2)
 }
 
 
-static void update_target(int target)
+static void update_target(int pm_qos_class)
 {
 	s32 extreme_value;
-	struct requirement_list *node;
+	struct pm_qos_request_list *node;
 	unsigned long flags;
 	int call_notifier = 0;
 
 	spin_lock_irqsave(&pm_qos_lock, flags);
-	extreme_value = pm_qos_array[target]->default_value;
+	extreme_value = pm_qos_array[pm_qos_class]->default_value;
 	list_for_each_entry(node,
-			&pm_qos_array[target]->requirements.list, list) {
-		extreme_value = pm_qos_array[target]->comparitor(
+			&pm_qos_array[pm_qos_class]->requests.list, list) {
+		extreme_value = pm_qos_array[pm_qos_class]->comparitor(
 				extreme_value, node->value);
 	}
-	if (atomic_read(&pm_qos_array[target]->target_value) != extreme_value) {
+	if (atomic_read(&pm_qos_array[pm_qos_class]->target_value) !=
+			extreme_value) {
 		call_notifier = 1;
-		atomic_set(&pm_qos_array[target]->target_value, extreme_value);
-		pr_debug(KERN_ERR "new target for qos %d is %d\n", target,
-			atomic_read(&pm_qos_array[target]->target_value));
+		atomic_set(&pm_qos_array[pm_qos_class]->target_value,
+				extreme_value);
+		pr_debug(KERN_ERR "new target for qos %d is %d\n", pm_qos_class,
+			atomic_read(&pm_qos_array[pm_qos_class]->target_value));
 	}
 	spin_unlock_irqrestore(&pm_qos_lock, flags);
 
 	if (call_notifier)
-		blocking_notifier_call_chain(pm_qos_array[target]->notifiers,
-			(unsigned long) extreme_value, NULL);
+		blocking_notifier_call_chain(
+				pm_qos_array[pm_qos_class]->notifiers,
+					(unsigned long) extreme_value, NULL);
 }
 
 static int register_pm_qos_misc(struct pm_qos_object *qos)
@@ -185,125 +189,113 @@ static int find_pm_qos_object_by_minor(int minor)
 }
 
 /**
- * pm_qos_requirement - returns current system wide qos expectation
+ * pm_qos_request - returns current system wide qos expectation
  * @pm_qos_class: identification of which qos value is requested
  *
  * This function returns the current target value in an atomic manner.
  */
-int pm_qos_requirement(int pm_qos_class)
+int pm_qos_request(int pm_qos_class)
 {
 	return atomic_read(&pm_qos_array[pm_qos_class]->target_value);
 }
-EXPORT_SYMBOL_GPL(pm_qos_requirement);
+EXPORT_SYMBOL_GPL(pm_qos_request);
 
 /**
- * pm_qos_add_requirement - inserts new qos request into the list
+ * pm_qos_add_request - inserts new qos request into the list
  * @pm_qos_class: identifies which list of qos request to us
- * @name: identifies the request
  * @value: defines the qos request
  *
  * This function inserts a new entry in the pm_qos_class list of requested qos
  * performance characteristics.  It recomputes the aggregate QoS expectations
- * for the pm_qos_class of parameters.
+ * for the pm_qos_class of parameters, and returns the pm_qos_request list
+ * element as a handle for use in updating and removal.  Call needs to save
+ * this handle for later use.
  */
-int pm_qos_add_requirement(int pm_qos_class, char *name, s32 value)
+struct pm_qos_request_list *pm_qos_add_request(int pm_qos_class, s32 value)
 {
-	struct requirement_list *dep;
+	struct pm_qos_request_list *dep;
 	unsigned long flags;
 
-	dep = kzalloc(sizeof(struct requirement_list), GFP_KERNEL);
+	dep = kzalloc(sizeof(struct pm_qos_request_list), GFP_KERNEL);
 	if (dep) {
 		if (value == PM_QOS_DEFAULT_VALUE)
 			dep->value = pm_qos_array[pm_qos_class]->default_value;
 		else
 			dep->value = value;
-		dep->name = kstrdup(name, GFP_KERNEL);
-		if (!dep->name)
-			goto cleanup;
+		dep->pm_qos_class = pm_qos_class;
 
 		spin_lock_irqsave(&pm_qos_lock, flags);
 		list_add(&dep->list,
-			&pm_qos_array[pm_qos_class]->requirements.list);
+			&pm_qos_array[pm_qos_class]->requests.list);
 		spin_unlock_irqrestore(&pm_qos_lock, flags);
 		update_target(pm_qos_class);
-
-		return 0;
 	}
 
-cleanup:
-	kfree(dep);
-	return -ENOMEM;
+	return dep;
 }
-EXPORT_SYMBOL_GPL(pm_qos_add_requirement);
+EXPORT_SYMBOL_GPL(pm_qos_add_request);
 
 /**
- * pm_qos_update_requirement - modifies an existing qos request
- * @pm_qos_class: identifies which list of qos request to us
- * @name: identifies the request
+ * pm_qos_update_request - modifies an existing qos request
+ * @pm_qos_req : handle to list element holding a pm_qos request to use
  * @value: defines the qos request
  *
- * Updates an existing qos requirement for the pm_qos_class of parameters along
+ * Updates an existing qos request for the pm_qos_class of parameters along
  * with updating the target pm_qos_class value.
  *
- * If the named request isn't in the list then no change is made.
+ * Attempts are made to make this code callable on hot code paths.
  */
-int pm_qos_update_requirement(int pm_qos_class, char *name, s32 new_value)
+void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req,
+		s32 new_value)
 {
 	unsigned long flags;
-	struct requirement_list *node;
 	int pending_update = 0;
+	s32 temp;
 
-	spin_lock_irqsave(&pm_qos_lock, flags);
-	list_for_each_entry(node,
-		&pm_qos_array[pm_qos_class]->requirements.list, list) {
-		if (strcmp(node->name, name) == 0) {
-			if (new_value == PM_QOS_DEFAULT_VALUE)
-				node->value =
-				pm_qos_array[pm_qos_class]->default_value;
-			else
-				node->value = new_value;
+	if (pm_qos_req) { /*guard against callers passing in null */
+		spin_lock_irqsave(&pm_qos_lock, flags);
+		if (new_value == PM_QOS_DEFAULT_VALUE)
+			temp = pm_qos_array[pm_qos_req->pm_qos_class]->
+				default_value;
+		else
+			temp = new_value;
+
+		if (temp != pm_qos_req->value) {
 			pending_update = 1;
-			break;
+			pm_qos_req->value = temp;
 		}
+		spin_unlock_irqrestore(&pm_qos_lock, flags);
 	}
-	spin_unlock_irqrestore(&pm_qos_lock, flags);
 	if (pending_update)
-		update_target(pm_qos_class);
-
-	return 0;
+		update_target(pm_qos_req->pm_qos_class);
 }
-EXPORT_SYMBOL_GPL(pm_qos_update_requirement);
+EXPORT_SYMBOL_GPL(pm_qos_update_request);
 
 /**
- * pm_qos_remove_requirement - modifies an existing qos request
- * @pm_qos_class: identifies which list of qos request to us
- * @name: identifies the request
+ * pm_qos_remove_request - modifies an existing qos request
+ * @pm_qos_req: handle to request list element
  *
- * Will remove named qos request from pm_qos_class list of parameters and
- * recompute the current target value for the pm_qos_class.
+ * Will remove pm qos request from the list of requests and
+ * recompute the current target value for the pm_qos_class.  Call this
+ * on slow code paths.
  */
-void pm_qos_remove_requirement(int pm_qos_class, char *name)
+void pm_qos_remove_request(struct pm_qos_request_list *pm_qos_req)
 {
 	unsigned long flags;
-	struct requirement_list *node;
-	int pending_update = 0;
+	int qos_class;
+
+	if (pm_qos_req == NULL)
+		return;
+		/* silent return to keep pcm code cleaner */
 
+	qos_class = pm_qos_req->pm_qos_class;
 	spin_lock_irqsave(&pm_qos_lock, flags);
-	list_for_each_entry(node,
-		&pm_qos_array[pm_qos_class]->requirements.list, list) {
-		if (strcmp(node->name, name) == 0) {
-			kfree(node->name);
-			list_del(&node->list);
-			kfree(node);
-			pending_update = 1;
-			break;
-		}
-	}
+	list_del(&pm_qos_req->list);
+	kfree(pm_qos_req);
 	spin_unlock_irqrestore(&pm_qos_lock, flags);
-	if (pending_update)
-		update_target(pm_qos_class);
+	update_target(qos_class);
 }
-EXPORT_SYMBOL_GPL(pm_qos_remove_requirement);
+EXPORT_SYMBOL_GPL(pm_qos_remove_request);
 
 /**
  * pm_qos_add_notifier - sets notification entry for changes to target value
@@ -313,7 +305,7 @@ EXPORT_SYMBOL_GPL(pm_qos_remove_requirement);
  * will register the notifier into a notification chain that gets called
  * upon changes to the pm_qos_class target value.
  */
- int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
+int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
 {
 	int retval;
 
@@ -343,21 +335,16 @@ int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
 }
 EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
 
-#define PID_NAME_LEN 32
-
 static int pm_qos_power_open(struct inode *inode, struct file *filp)
 {
-	int ret;
 	long pm_qos_class;
-	char name[PID_NAME_LEN];
 
 	pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
 	if (pm_qos_class >= 0) {
-		filp->private_data = (void *)pm_qos_class;
-		snprintf(name, PID_NAME_LEN, "process_%d", current->pid);
-		ret = pm_qos_add_requirement(pm_qos_class, name,
-					PM_QOS_DEFAULT_VALUE);
-		if (ret >= 0)
+		filp->private_data = (void *) pm_qos_add_request(pm_qos_class,
+				PM_QOS_DEFAULT_VALUE);
+
+		if (filp->private_data)
 			return 0;
 	}
 	return -EPERM;
@@ -365,32 +352,40 @@ static int pm_qos_power_open(struct inode *inode, struct file *filp)
 
 static int pm_qos_power_release(struct inode *inode, struct file *filp)
 {
-	int pm_qos_class;
-	char name[PID_NAME_LEN];
+	struct pm_qos_request_list *req;
 
-	pm_qos_class = (long)filp->private_data;
-	snprintf(name, PID_NAME_LEN, "process_%d", current->pid);
-	pm_qos_remove_requirement(pm_qos_class, name);
+	req = (struct pm_qos_request_list *)filp->private_data;
+	pm_qos_remove_request(req);
 
 	return 0;
 }
 
+
 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 		size_t count, loff_t *f_pos)
 {
 	s32 value;
-	int pm_qos_class;
-	char name[PID_NAME_LEN];
-
-	pm_qos_class = (long)filp->private_data;
-	if (count != sizeof(s32))
+	int x;
+	char ascii_value[11];
+	struct pm_qos_request_list *pm_qos_req;
+
+	if (count == sizeof(s32)) {
+		if (copy_from_user(&value, buf, sizeof(s32)))
+			return -EFAULT;
+	} else if (count == 11) { /* len('0x12345678/0') */
+		if (copy_from_user(ascii_value, buf, 11))
+			return -EFAULT;
+		x = sscanf(ascii_value, "%x", &value);
+		if (x != 1)
+			return -EINVAL;
+		pr_debug(KERN_ERR "%s, %d, 0x%x\n", ascii_value, x, value);
+	} else
 		return -EINVAL;
-	if (copy_from_user(&value, buf, sizeof(s32)))
-		return -EFAULT;
-	snprintf(name, PID_NAME_LEN, "process_%d", current->pid);
-	pm_qos_update_requirement(pm_qos_class, name, value);
 
-	return  sizeof(s32);
+	pm_qos_req = (struct pm_qos_request_list *)filp->private_data;
+	pm_qos_update_request(pm_qos_req, value);
+
+	return count;
 }
 
 
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 875c8de..88f95e7 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -495,7 +495,7 @@ void ieee80211_recalc_ps(struct ieee80211_local *local, s32 latency)
 		s32 beaconint_us;
 
 		if (latency < 0)
-			latency = pm_qos_requirement(PM_QOS_NETWORK_LATENCY);
+			latency = pm_qos_request(PM_QOS_NETWORK_LATENCY);
 
 		beaconint_us = ieee80211_tu_to_usec(
 					found->vif.bss_conf.beacon_int);
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 0d428d0..cbe815d 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -648,9 +648,6 @@ int snd_pcm_new_stream(struct snd_pcm *pcm, int stream, int substream_count)
 		substream->number = idx;
 		substream->stream = stream;
 		sprintf(substream->name, "subdevice #%i", idx);
-		snprintf(substream->latency_id, sizeof(substream->latency_id),
-			 "ALSA-PCM%d-%d%c%d", pcm->card->number, pcm->device,
-			 (stream ? 'c' : 'p'), idx);
 		substream->buffer_bytes_max = UINT_MAX;
 		if (prev == NULL)
 			pstr->substream = substream;
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 20b5982..192dd40 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -484,11 +484,13 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
 	snd_pcm_timer_resolution_change(substream);
 	runtime->status->state = SNDRV_PCM_STATE_SETUP;
 
-	pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY,
-				substream->latency_id);
+	if (substream->latency_pm_qos_req) {
+		pm_qos_remove_request(substream->latency_pm_qos_req);
+		substream->latency_pm_qos_req = NULL;
+	}
 	if ((usecs = period_to_usecs(runtime)) >= 0)
-		pm_qos_add_requirement(PM_QOS_CPU_DMA_LATENCY,
-					substream->latency_id, usecs);
+		substream->latency_pm_qos_req = pm_qos_add_request(
+					PM_QOS_CPU_DMA_LATENCY, usecs);
 	return 0;
  _error:
 	/* hardware might be unuseable from this time,
@@ -543,8 +545,8 @@ static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
 	if (substream->ops->hw_free)
 		result = substream->ops->hw_free(substream);
 	runtime->status->state = SNDRV_PCM_STATE_OPEN;
-	pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY,
-		substream->latency_id);
+	pm_qos_remove_request(substream->latency_pm_qos_req);
+	substream->latency_pm_qos_req = NULL;
 	return result;
 }
 
-- 
1.6.3.3

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