X-Git-Url: http://git.cascardo.eti.br/?p=cascardo%2Fkernel%2Fsamples%2Fworkqueue%2F.git;a=blobdiff_plain;f=block_wq.c;fp=block_wq.c;h=ae6d8abf8b38a7b2aa13eb98f58f9a363535971d;hp=0000000000000000000000000000000000000000;hb=271a17e550236d7cfc14385a1b20f692e23de0af;hpb=22ee84b81b928deceb560578b1ff40bbcc7a6a0f

diff --git a/block_wq.c b/block_wq.c
new file mode 100644
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--- /dev/null
+++ b/block_wq.c
@@ -0,0 +1,68 @@
+/*
+ *  Copyright (C) 2010  Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * This code demonstrates why a work should not block for too long.
+ * This is worse in the case that the work is scheduled in keventd.
+ */
+
+#include <linux/module.h>
+#include <linux/workqueue.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Thadeu Lima de Souza Cascardo");
+
+static void work_block(struct work_struct *work)
+{
+	unsigned long tmp = jiffies + 5 * HZ;
+	printk(KERN_INFO "Blocking other works in the queue\n");
+	printk(KERN_INFO "Executing task in CPU %d\n", smp_processor_id());
+	/* We also kick the CPU high */
+	while (!time_after(jiffies, tmp))
+		cpu_relax();
+}
+
+static void work_print(struct work_struct *work)
+{
+	printk(KERN_INFO "Phew! That was waiting!\n");
+	printk(KERN_INFO "Task done in CPU %d\n", smp_processor_id());
+}
+
+static struct workqueue_struct *block_wq;
+static DECLARE_WORK(block_work, work_block);
+static DECLARE_WORK(print_work, work_print);
+
+static int block_wq_init(void)
+{
+	block_wq = create_workqueue("block_wq");
+	if (!block_wq)
+		return -ENOMEM;
+	printk(KERN_INFO "Queueing task in CPU %d\n", get_cpu());
+	put_cpu();
+	queue_work(block_wq, &block_work);
+	queue_work(block_wq, &print_work);
+	return 0;
+}
+
+static void block_wq_exit(void)
+{
+	destroy_workqueue(block_wq);
+}
+
+module_init(block_wq_init);
+module_exit(block_wq_exit);