Add stupid tests.

[~madcoder/pwqr.git] / kernel / pwqr.c

diff --git a/kernel/pwqr.c b/kernel/pwqr.c
index 0d6b42c..8248482 100644 (file)
--- a/kernel/pwqr.c
+++ b/kernel/pwqr.c
@@ -33,16 +33,50 @@
 #include <linux/timer.h>
 #include <linux/uaccess.h>
 #include <linux/wait.h>
 #include <linux/timer.h>
 #include <linux/uaccess.h>
 #include <linux/wait.h>

+#include <linux/version.h>
+
+/*
+ * The pthread workqueue regulator code is for now written as a proof of
+ * concept module, meant to work with 2.6.23+ kernels or redhat5 ones.
+ *
+ * For now it uses a device /dev/pwq, which spawns magic file-descriptors
+ * supporting a few ioctl operations (see Documentation/pwqr.adoc shipped in
+ * the same git repository).
+ *
+ * This code is meant to be merged into mainline, but after the following
+ * changes, kept here as a "todolist":
+ *
+ *   - get rid of the device stuff (which is 100% of the init code for 2.6.23
+ *     kernels);
+ *
+ *   - resubmit the patch that makes it possible to call
+ *     preempt_notifier_unregister from sched_in/sched_out (just a matter of a
+ *     hlist_for_each_safe instead of hlist_for_each), and fix
+ *     pwqr_task_release to not require RCU anymore. It makes
+ *     pwqr_preempt_noop_ops go away.
+ *
+ *   - think about the possibility to add a pwq_notifier pointer directly into
+ *     the task_struct, thought it's not *that* necessary, it grows the
+ *     structure for a speed gain we don't really need (making pwqr_ctl
+ *     faster). I think it's okay to crawl the preempt_notifier list instead.
+ *     We may want to add nice "macros" for that though.
+ *
+ *   - replace the ioctl with a pwqr_ctl syscall
+ *
+ *   - create a pwqr_create() syscall to create a pwqr file-descriptor.
+ *
+ * Summary: most of the code should be untouched or almost not changed,
+ * pwqr_ioctl adapted to become a syscall, and the module boilerplate replaced
+ * with pwqr_create() and file-descriptor creation boilerplate instead. But
+ * looking at fs/eventfd.c this looks rather simple.
+ */

 
 #ifndef CONFIG_PREEMPT_NOTIFIERS
 #  error PWQ module requires CONFIG_PREEMPT_NOTIFIERS
 
 #ifndef CONFIG_PREEMPT_NOTIFIERS
 #  error PWQ module requires CONFIG_PREEMPT_NOTIFIERS

-#endif
+#else

 
 #include "pwqr.h"
 
 
 #include "pwqr.h"
 

-#define PWQR_HASH_BITS         5
-#define PWQR_HASH_SIZE         (1 << PWQR_HASH_BITS)
-

 #define PWQR_UC_DELAY          (HZ / 10)
 #define PWQR_OC_DELAY          (HZ / 20)
 
 #define PWQR_UC_DELAY          (HZ / 10)
 #define PWQR_OC_DELAY          (HZ / 20)
 


@@ -51,10 +85,19 @@
 #define PWQR_STATE_OC          2
 #define PWQR_STATE_DEAD                (-1)
 
 #define PWQR_STATE_OC          2
 #define PWQR_STATE_DEAD                (-1)
 

-struct pwqr_task_bucket {
-       spinlock_t              lock;
-       struct hlist_head       tasks;
-};
+/*
+ * This is the first inclusion of CONFIG_PREEMPT_NOTIFIERS in the kernel.
+ *
+ * Though I want it to work on older redhat 5 kernels, that have an emulation
+ * of the feature but not implemented the same way, and instead of linking the
+ * preempt_notifiers from the task_struct directly, they have a private
+ * h-table I don't have access to, so I need my own too.
+ *
+ * For vanilla kernels we crawl through the task_struct::preempt_notifiers
+ * hlist until we find our entry, this list is often very short, and it's no
+ * slower than the global h-table which also crawls a list anyway.
+ */
+#define IS_PRE_2_6_23    (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 23))

 
 struct pwqr_sb {
        struct kref             kref;
 
 struct pwqr_sb {
        struct kref             kref;


@@ -76,18 +119,32 @@ struct pwqr_sb {
 
 struct pwqr_task {
        struct preempt_notifier notifier;
 
 struct pwqr_task {
        struct preempt_notifier notifier;

-       struct hlist_node       link;
+       struct pwqr_sb         *sb;

        struct rcu_head         rcu;
        struct rcu_head         rcu;

+#if IS_PRE_2_6_23
+       struct hlist_node       link;

        struct task_struct     *task;
        struct task_struct     *task;

-       struct pwqr_sb         *sb;
+#endif
+};
+
+#if IS_PRE_2_6_23
+
+#define PWQR_HASH_BITS         5
+#define PWQR_HASH_SIZE         (1 << PWQR_HASH_BITS)
+
+struct pwqr_task_bucket {
+       spinlock_t              lock;
+       struct hlist_head       tasks;

 };
 
 };
 

+static struct pwqr_task_bucket pwqr_tasks_hash[PWQR_HASH_SIZE];
+#endif
+

 /*
  * Global variables
  */
 static struct class           *pwqr_class;
 static int                     pwqr_major;
 /*
  * Global variables
  */
 static struct class           *pwqr_class;
 static int                     pwqr_major;

-static struct pwqr_task_bucket pwqr_tasks_hash[PWQR_HASH_SIZE];

 static struct preempt_ops      pwqr_preempt_running_ops;
 static struct preempt_ops      pwqr_preempt_blocked_ops;
 static struct preempt_ops      pwqr_preempt_noop_ops;
 static struct preempt_ops      pwqr_preempt_running_ops;
 static struct preempt_ops      pwqr_preempt_blocked_ops;
 static struct preempt_ops      pwqr_preempt_noop_ops;


@@ -135,6 +192,7 @@ static void pwqr_sb_timer_cb(unsigned long arg)
                        wake_up_locked(&sb->wqh);
        }
        if (sb->running > sb->concurrency) {
                        wake_up_locked(&sb->wqh);
        }
        if (sb->running > sb->concurrency) {

+               printk(KERN_DEBUG "wake up poll");

                wake_up_poll(&sb->wqh_poll, POLLIN);
        }
        pwqr_sb_unlock_irqrestore(sb, flags);
                wake_up_poll(&sb->wqh_poll, POLLIN);
        }
        pwqr_sb_unlock_irqrestore(sb, flags);


@@ -187,6 +245,7 @@ static inline void pwqr_sb_put(struct pwqr_sb *sb)
 /*****************************************************************************
  * tasks
  */
 /*****************************************************************************
  * tasks
  */

+#if IS_PRE_2_6_23

 static inline struct pwqr_task_bucket *task_hbucket(struct task_struct *task)
 {
        return &pwqr_tasks_hash[hash_ptr(task, PWQR_HASH_BITS)];
 static inline struct pwqr_task_bucket *task_hbucket(struct task_struct *task)
 {
        return &pwqr_tasks_hash[hash_ptr(task, PWQR_HASH_BITS)];


@@ -206,10 +265,29 @@ static struct pwqr_task *pwqr_task_find(struct task_struct *task)
        spin_unlock(&b->lock);
        return pwqt;
 }
        spin_unlock(&b->lock);
        return pwqt;
 }

+#else
+static struct pwqr_task *pwqr_task_find(struct task_struct *task)
+{
+       struct hlist_node       *node;
+       struct preempt_notifier *it;
+       struct pwqr_task        *pwqt = NULL;
+
+       hlist_for_each_entry(it, node, &task->preempt_notifiers, link) {
+               if (it->ops == &pwqr_preempt_running_ops ||
+                   it->ops == &pwqr_preempt_blocked_ops ||
+                   it->ops == &pwqr_preempt_noop_ops)
+               {
+                       pwqt = container_of(it, struct pwqr_task, notifier);
+                       break;
+               }
+       }
+
+       return pwqt;
+}
+#endif

 
 static struct pwqr_task *pwqr_task_create(struct task_struct *task)
 {
 
 static struct pwqr_task *pwqr_task_create(struct task_struct *task)
 {

-       struct pwqr_task_bucket *b = task_hbucket(task);

        struct pwqr_task *pwqt;
 
        pwqt = kmalloc(sizeof(*pwqt), GFP_KERNEL);
        struct pwqr_task *pwqt;
 
        pwqt = kmalloc(sizeof(*pwqt), GFP_KERNEL);


@@ -218,12 +296,16 @@ static struct pwqr_task *pwqr_task_create(struct task_struct *task)
 
        preempt_notifier_init(&pwqt->notifier, &pwqr_preempt_running_ops);
        preempt_notifier_register(&pwqt->notifier);
 
        preempt_notifier_init(&pwqt->notifier, &pwqr_preempt_running_ops);
        preempt_notifier_register(&pwqt->notifier);

-       pwqt->task = task;
-
-       spin_lock(&b->lock);
-       hlist_add_head(&pwqt->link, &b->tasks);
-       spin_unlock(&b->lock);
-
+#if IS_PRE_2_6_23
+       {
+               struct pwqr_task_bucket *b = task_hbucket(task);
+
+               pwqt->task = task;
+               spin_lock(&b->lock);
+               hlist_add_head(&pwqt->link, &b->tasks);
+               spin_unlock(&b->lock);
+       }
+#endif

        return pwqt;
 }
 
        return pwqt;
 }
 


@@ -259,11 +341,13 @@ static void pwqr_task_attach(struct pwqr_task *pwqt, struct pwqr_sb *sb)
 __cold
 static void pwqr_task_release(struct pwqr_task *pwqt, bool from_notifier)
 {
 __cold
 static void pwqr_task_release(struct pwqr_task *pwqt, bool from_notifier)
 {

+#if IS_PRE_2_6_23

        struct pwqr_task_bucket *b = task_hbucket(pwqt->task);
 
        spin_lock(&b->lock);
        hlist_del(&pwqt->link);
        spin_unlock(&b->lock);
        struct pwqr_task_bucket *b = task_hbucket(pwqt->task);
 
        spin_lock(&b->lock);
        hlist_del(&pwqt->link);
        spin_unlock(&b->lock);

+#endif

        pwqt->notifier.ops = &pwqr_preempt_noop_ops;
 
        if (from_notifier) {
        pwqt->notifier.ops = &pwqr_preempt_noop_ops;
 
        if (from_notifier) {


@@ -274,7 +358,7 @@ static void pwqr_task_release(struct pwqr_task *pwqt, bool from_notifier)
                 * callbacks if we're not dying, it'll panic on the next
                 * sched_{in,out} call.
                 */
                 * callbacks if we're not dying, it'll panic on the next
                 * sched_{in,out} call.
                 */

-               BUG_ON(!(pwqt->task->state & TASK_DEAD));
+               BUG_ON(!(current->state & TASK_DEAD));

                kfree_rcu(pwqt, rcu);
        } else {
                preempt_notifier_unregister(&pwqt->notifier);
                kfree_rcu(pwqt, rcu);
        } else {
                preempt_notifier_unregister(&pwqt->notifier);


@@ -310,11 +394,11 @@ static void pwqr_task_blocked_sched_in(struct preempt_notifier *notifier, int cp
 }
 
 static void pwqr_task_sched_out(struct preempt_notifier *notifier,
 }
 
 static void pwqr_task_sched_out(struct preempt_notifier *notifier,

-                              struct task_struct *next)
+                               struct task_struct *next)

 {
        struct pwqr_task   *pwqt = container_of(notifier, struct pwqr_task, notifier);
        struct pwqr_sb     *sb   = pwqt->sb;
 {
        struct pwqr_task   *pwqt = container_of(notifier, struct pwqr_task, notifier);
        struct pwqr_sb     *sb   = pwqt->sb;

-       struct task_struct *p    = pwqt->task;
+       struct task_struct *p    = current;

 
        if (unlikely(p->state & TASK_DEAD) || unlikely(sb->state < 0)) {
                pwqr_task_detach(pwqt, sb);
 
        if (unlikely(p->state & TASK_DEAD) || unlikely(sb->state < 0)) {
                pwqr_task_detach(pwqt, sb);


@@ -631,26 +715,26 @@ static long pwqr_ioctl(struct file *filp, unsigned command, unsigned long arg)
        int rc = 0;
 
        switch (command) {
        int rc = 0;
 
        switch (command) {

-       case PWQR_GET_CONC:
+       case PWQR_CTL_GET_CONC:

                return sb->concurrency;
                return sb->concurrency;

-       case PWQR_SET_CONC:
+       case PWQR_CTL_SET_CONC:

                return do_pwqr_set_conc(sb, (int)arg);
 
                return do_pwqr_set_conc(sb, (int)arg);
 

-       case PWQR_WAKE:
-       case PWQR_WAKE_OC:
-               return do_pwqr_wake(sb, command == PWQR_WAKE_OC, (int)arg);
+       case PWQR_CTL_WAKE:
+       case PWQR_CTL_WAKE_OC:
+               return do_pwqr_wake(sb, command == PWQR_CTL_WAKE_OC, (int)arg);

 
 

-       case PWQR_WAIT:
-       case PWQR_PARK:
-       case PWQR_REGISTER:
-       case PWQR_UNREGISTER:
+       case PWQR_CTL_WAIT:
+       case PWQR_CTL_PARK:
+       case PWQR_CTL_REGISTER:
+       case PWQR_CTL_UNREGISTER:

                break;
        default:
                return -EINVAL;
        }
 
        pwqt = pwqr_task_find(task);
                break;
        default:
                return -EINVAL;
        }
 
        pwqt = pwqr_task_find(task);

-       if (command == PWQR_UNREGISTER)
+       if (command == PWQR_CTL_UNREGISTER)

                return do_pwqr_unregister(sb, pwqt);
 
        if (pwqt == NULL) {
                return do_pwqr_unregister(sb, pwqt);
 
        if (pwqt == NULL) {


@@ -664,18 +748,13 @@ static long pwqr_ioctl(struct file *filp, unsigned command, unsigned long arg)
        }
 
        switch (command) {
        }
 
        switch (command) {

-       case PWQR_WAIT:
+       case PWQR_CTL_WAIT:

                rc = do_pwqr_wait(sb, pwqt, true, (struct pwqr_ioc_wait __user *)arg);
                break;
                rc = do_pwqr_wait(sb, pwqt, true, (struct pwqr_ioc_wait __user *)arg);
                break;

-       case PWQR_PARK:
+       case PWQR_CTL_PARK:

                rc = do_pwqr_wait(sb, pwqt, false, NULL);
                break;
        }
                rc = do_pwqr_wait(sb, pwqt, false, NULL);
                break;
        }

-
-       if (unlikely(sb->state < 0)) {
-               pwqr_task_detach(pwqt, pwqt->sb);
-               return -EBADFD;
-       }

        return rc;
 }
 
        return rc;
 }
 


@@ -697,12 +776,14 @@ static const struct file_operations pwqr_dev_fops = {
  */
 static int __init pwqr_start(void)
 {
  */
 static int __init pwqr_start(void)
 {

+#if IS_PRE_2_6_23

        int i;
 
        for (i = 0; i < PWQR_HASH_SIZE; i++) {
                spin_lock_init(&pwqr_tasks_hash[i].lock);
                INIT_HLIST_HEAD(&pwqr_tasks_hash[i].tasks);
        }
        int i;
 
        for (i = 0; i < PWQR_HASH_SIZE; i++) {
                spin_lock_init(&pwqr_tasks_hash[i].lock);
                INIT_HLIST_HEAD(&pwqr_tasks_hash[i].tasks);
        }

+#endif

 
        /* Register as a character device */
        pwqr_major = register_chrdev(0, "pwqr", &pwqr_dev_fops);
 
        /* Register as a character device */
        pwqr_major = register_chrdev(0, "pwqr", &pwqr_dev_fops);


@@ -737,5 +818,6 @@ module_exit(pwqr_end);
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Pierre Habouzit <pierre.habouzit@intersec.com>");
 MODULE_DESCRIPTION("PThreads Work Queues Regulator");
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Pierre Habouzit <pierre.habouzit@intersec.com>");
 MODULE_DESCRIPTION("PThreads Work Queues Regulator");

+#endif

 
 // vim:noet:sw=8:cinoptions+=\:0,L-1,=1s:
 
 // vim:noet:sw=8:cinoptions+=\:0,L-1,=1s: