core: add stop_io method

Signed-off-by: Alessandro Rubini <rubini@gnudd.com> Acked-by: Federico Vaga <federico.vaga@gmail.com>

core: add stop_io method
Signed-off-by: Alessandro Rubini <rubini@gnudd.com> Acked-by: Federico Vaga <federico.vaga@gmail.com>
713d29ad · Alessandro Rubini · 4e41db28 · 713d29ad · 713d29ad · 713d29ad
Commit 713d29ad authored Jan 08, 2013 by Alessandro Rubini
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zio-manual.in doc/zio-manual.in +19 -8

helpers.c helpers.c +2 -0

zio-trigger.h include/linux/zio-trigger.h +3 -2

zio.h include/linux/zio.h +2 -1

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--- a/doc/zio-manual.in
+++ b/doc/zio-manual.in
@@ -915,6 +915,9 @@ the fields are not yet being filled by the core.
        5-bit samples aligned in 32-bit words. The number of bits is a
        device attribute: drivers may allow to change them at run-time.
        The sample size is however immutable for the lifetime of a cset.
+        An input driver can reduce @t{nsamples} in the current control,
+        in order to return a shorter block than requested (the value
+        is re-initialized every time a trigger is armed).

 @cindex address of a channel
 @cindex channel, address
@@ -1758,6 +1761,15 @@ or used by the developer are:
        cset code will call @code{zio_trigger_data_done()} at a later time.
        Other return values are used to report real errors.

+@cindex stop_io
+@item void (*stop_io)(struct zio_cset *cset)
+
+	The function, if present, is called when an armed trigger is
+        aborted.  The driver will need to implement this method
+        if it wants to return a partially-filled block.  The method
+        is called with the lock taken, and can call @t{zio_generic_data_done},
+        which is the locked back-end of @t{zio_trigger_data_done}).
+
 @cindex sample size
 @item  unsigned ssize

@@ -2158,15 +2170,14 @@ The detailed meaning of the operations is as follows:
 	Abort, if defined, is called when an already-armed trigger event
        must be aborted. This happens, for example, because event
        parameters changed (e.g., the block size).  The method must
-        dispose the @i{active_block} for each channel, and set the
-        pointer to NULL. The trigger may perform @i{data_done} for
-        partially-filled block. The method
+        call @t{cset->stop_io} if not NULL and 
+        dispose the @i{active_block} for each channel, setting the
+        pointer to NULL. Please check how it is used in @t{helpers.c}.
+        The method
        is called while holding the cset lock and cannot fail nor sleep.
-
-@c  The trigger will usually call the @i{stop_io}
-@c        device method and optionally may perform @i{data_done} for
-@c        partially-filled  blocks. The method
-@c        is called while holding the cset lock and cannot fail nor sleep
+        A trigger implementing this method will usually call
+        the @i{stop_io} cset method. See the generic abort implementation
+        for reference.

 @item change_status
        The method, if defined, is called when the trigger is enabled or

--- a/helpers.c
+++ b/helpers.c
@@ -50,6 +50,8 @@ int zio_trigger_abort_disable(struct zio_cset *cset, int disable)
 	if (ti->flags & ZIO_TI_ARMED) {
 		if (ti->t_op->abort)
 			ti->t_op->abort(ti);
+		else if (ti->cset->stop_io)
+			ti->cset->stop_io(ti->cset);
 		else
 			__zio_internal_abort_free(cset);
 		ti->flags &= (~ZIO_TI_ARMED);

--- a/include/linux/zio-trigger.h
+++ b/include/linux/zio-trigger.h
@@ -110,8 +110,9 @@ int zio_trigger_abort_disable(struct zio_cset *cset, int disable);

 /*
 * This generic_data_done can be used by triggers, as part of their own.
- * If not trigger-specific function is specified, the core calls this one.
- * When data_done is called, the trigger is armed and the cset lock is taken
+ * If no trigger-specific function is specified, the core calls this one.
+ * This can also be called by cset->stop_io to return partial blocks.
+ * The function is called while holding the cset spin lock.
 */
 static inline void zio_generic_data_done(struct zio_cset *cset)
 {

--- a/include/linux/zio.h
+++ b/include/linux/zio.h
@@ -175,7 +175,8 @@ struct zio_cset {
 	struct zio_trigger_type *trig;		/* trigger type for ti*/
 	struct zio_ti		*ti;		/* trigger instance */
 	int			(*raw_io)(struct zio_cset *cset);
-	spinlock_t		lock;		 /* for flags */
+	void			(*stop_io)(struct zio_cset *cset);
+	spinlock_t		lock;		 /* for flags and triggers */

 	unsigned		ssize;		/* sample size (bytes) */
 	unsigned		index;		/* index within parent */