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authorJames Bottomley <James.Bottomley@steeleye.com>2006-02-14 19:42:07 +0300
committer <jejb@mulgrave.il.steeleye.com>2006-02-14 20:14:26 +0300
commitfaead26d7a06605add627f29aee73ba654ce11f9 (patch)
treecd809c6e5601caefb66e614ee1f06417819d2151
parente2230eac17486e2ee07091d54d898eb40bcd0fdd (diff)
downloadlinux-faead26d7a06605add627f29aee73ba654ce11f9.tar.xz
[PATCH] add scsi_execute_in_process_context() API
We have several points in the SCSI stack (primarily for our device functions) where we need to guarantee process context, but (given the place where the last reference was released) we cannot guarantee this. This API gets around the issue by executing the function directly if the caller has process context, but scheduling a workqueue to execute in process context if the caller doesn't have it. Unfortunately, it requires memory allocation in interrupt context, but it's better than what we have previously. The true solution will require a bit of re-engineering, so isn't appropriate for 2.6.16. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
-rw-r--r--drivers/scsi/scsi_lib.c59
-rw-r--r--include/scsi/scsi.h2
2 files changed, 61 insertions, 0 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 4a602853a98e..4362dcde74af 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -16,6 +16,7 @@
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/delay.h>
+#include <linux/hardirq.h>
#include <scsi/scsi.h>
#include <scsi/scsi_dbg.h>
@@ -2248,3 +2249,61 @@ scsi_target_unblock(struct device *dev)
device_for_each_child(dev, NULL, target_unblock);
}
EXPORT_SYMBOL_GPL(scsi_target_unblock);
+
+
+struct work_queue_work {
+ struct work_struct work;
+ void (*fn)(void *);
+ void *data;
+};
+
+static void execute_in_process_context_work(void *data)
+{
+ void (*fn)(void *data);
+ struct work_queue_work *wqw = data;
+
+ fn = wqw->fn;
+ data = wqw->data;
+
+ kfree(wqw);
+
+ fn(data);
+}
+
+/**
+ * scsi_execute_in_process_context - reliably execute the routine with user context
+ * @fn: the function to execute
+ * @data: data to pass to the function
+ *
+ * Executes the function immediately if process context is available,
+ * otherwise schedules the function for delayed execution.
+ *
+ * Returns: 0 - function was executed
+ * 1 - function was scheduled for execution
+ * <0 - error
+ */
+int scsi_execute_in_process_context(void (*fn)(void *data), void *data)
+{
+ struct work_queue_work *wqw;
+
+ if (!in_interrupt()) {
+ fn(data);
+ return 0;
+ }
+
+ wqw = kmalloc(sizeof(struct work_queue_work), GFP_ATOMIC);
+
+ if (unlikely(!wqw)) {
+ printk(KERN_ERR "Failed to allocate memory\n");
+ WARN_ON(1);
+ return -ENOMEM;
+ }
+
+ INIT_WORK(&wqw->work, execute_in_process_context_work, wqw);
+ wqw->fn = fn;
+ wqw->data = data;
+ schedule_work(&wqw->work);
+
+ return 1;
+}
+EXPORT_SYMBOL_GPL(scsi_execute_in_process_context);
diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
index c60b8ff2f5e4..9c331258bc27 100644
--- a/include/scsi/scsi.h
+++ b/include/scsi/scsi.h
@@ -433,4 +433,6 @@ struct scsi_lun {
/* Used to obtain the PCI location of a device */
#define SCSI_IOCTL_GET_PCI 0x5387
+int scsi_execute_in_process_context(void (*fn)(void *data), void *data);
+
#endif /* _SCSI_SCSI_H */