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Re: [Minios-devel] [UNIKRAFT PATCH v2 5/6] lib/ukblkdev: Synchronous requests interface
Hey,
I like this new version of this patch. However, I have a few comments to
your uk_blkreq_is_done() and uk_blkreq_init() helpers.
Thanks,
Simon
On 01.07.19 12:04, Roxana Nicolescu wrote:
This patch introduces sync operations.
It requires the use of semaphore in the implementation.
Signed-off-by: Roxana Nicolescu <nicolescu.roxana1996@xxxxxxxxx>
---
lib/ukblkdev/Config.uk | 9 ++++++
lib/ukblkdev/blkdev.c | 58 +++++++++++++++++++++++++++++++++++
lib/ukblkdev/exportsyms.uk | 5 +++
lib/ukblkdev/include/uk/blkdev.h | 50 ++++++++++++++++++++++++++++++
lib/ukblkdev/include/uk/blkdev_core.h | 3 +-
lib/ukblkdev/include/uk/blkreq.h | 36 ++++++++++++++++++++++
6 files changed, 160 insertions(+), 1 deletion(-)
diff --git a/lib/ukblkdev/Config.uk b/lib/ukblkdev/Config.uk
index f0c89654..d5c96090 100644
--- a/lib/ukblkdev/Config.uk
+++ b/lib/ukblkdev/Config.uk
@@ -25,4 +25,13 @@ if LIBUKBLKDEV
When this option is enabled a dispatcher thread is
allocated for each configured queue.
libuksched is required for this option.
+
+ config LIBUKBLKDEV_SYNC_IO_BLOCKED_WAITING
+ bool "Synchronous I/O API"
+ default n
+ select LIBUKSCHED
+ select LIBUKLOCK
+ select LIBUKLOCK_SEMAPHORE
+ help
+ Use semaphore for waiting after a request I/O is done.
endif
diff --git a/lib/ukblkdev/blkdev.c b/lib/ukblkdev/blkdev.c
index a92b29f1..21346d50 100644
--- a/lib/ukblkdev/blkdev.c
+++ b/lib/ukblkdev/blkdev.c
@@ -408,3 +408,61 @@ int uk_blkdev_queue_finish_reqs(struct uk_blkdev *dev,
return dev->finish_reqs(dev, dev->_queue[queue_id]);
}
+
+#if CONFIG_LIBUKBLKDEV_SYNC_IO_BLOCKED_WAITING
+/**
+ * Used for sending a synchronous request.
+ */
+struct uk_blkdev_sync_io_request {
+ struct uk_blkreq req; /* Request structure. */
+
+ /* Semaphore used for waiting after the response is done. */
+ struct uk_semaphore s;
+};
+
+static void __sync_io_callback(struct uk_blkreq *req,
+ void *cookie_callback)
+{
+ struct uk_blkdev_sync_io_request *sync_io_req;
+
+ UK_ASSERT(req);
+ UK_ASSERT(cookie_callback);
+
+ sync_io_req = (struct uk_blkdev_sync_io_request *)cookie_callback;
+ uk_semaphore_up(&sync_io_req->s);
+}
+
+int uk_blkdev_sync_io(struct uk_blkdev *dev,
+ uint16_t queue_id,
+ enum uk_blkreq_op operation,
+ __sector start_sector,
+ __sector nb_sectors,
+ void *buf)
+{
+ struct uk_blkreq *req;
+ int rc = 0;
+ struct uk_blkdev_sync_io_request sync_io_req;
+
+ UK_ASSERT(dev != NULL);
+ UK_ASSERT(queue_id < CONFIG_LIBUKBLKDEV_MAXNBQUEUES);
+ UK_ASSERT(dev->_data);
+ UK_ASSERT(dev->submit_one);
+ UK_ASSERT(dev->_data->state == UK_BLKDEV_RUNNING);
+ UK_ASSERT(!PTRISERR(dev->_queue[queue_id]));
+
+ req = &sync_io_req.req;
+ uk_blkreq_init(req, operation, start_sector, nb_sectors,
+ __sync_io_callback, (void *)&sync_io_req, buf);
+ uk_semaphore_init(&sync_io_req.s, 0);
+
+ rc = uk_blkdev_queue_submit_one(dev, queue_id, req);
+ if (unlikely(!uk_blkdev_status_successful(rc))) {
+ uk_pr_err("blkdev%"PRIu16"-q%"PRIu16": Failed to submit I/O req:
%d\n",
+ dev->_data->id, queue_id, rc);
+ return rc;
+ }
+
+ uk_semaphore_down(&sync_io_req.s);
+ return req->result;
+}
+#endif
diff --git a/lib/ukblkdev/exportsyms.uk b/lib/ukblkdev/exportsyms.uk
index 33402f78..85135b95 100644
--- a/lib/ukblkdev/exportsyms.uk
+++ b/lib/ukblkdev/exportsyms.uk
@@ -19,3 +19,8 @@ uk_blkdev_sectors
uk_blkdev_ioalign
uk_blkdev_queue_submit_one
uk_blkdev_queue_finish_reqs
+uk_blkreq_init
+uk_blkdev_sync_io
+uk_blkdev_sync_read
+uk_blkdev_sync_write
uk_blkreq_init, uk_blkdev_sync_read, and uk_blkdev_sync_write are not
needed to be listed in exportsyms.uk. It doesn't hurt but they are just
defined as macro and static inline function in the header.
+uk_blkreq_is_done
diff --git a/lib/ukblkdev/include/uk/blkdev.h b/lib/ukblkdev/include/uk/blkdev.h
index b941911c..ad0f2629 100644
--- a/lib/ukblkdev/include/uk/blkdev.h
+++ b/lib/ukblkdev/include/uk/blkdev.h
@@ -421,6 +421,56 @@ int uk_blkdev_queue_submit_one(struct uk_blkdev *dev,
uint16_t queue_id,
*/
int uk_blkdev_queue_finish_reqs(struct uk_blkdev *dev, uint16_t queue_id);
+#if CONFIG_LIBUKBLKDEV_SYNC_IO_BLOCKED_WAITING
+/**
+ * Make a sync io request on a specific queue.
+ * `uk_blkdev_queue_finish_reqs()` must be called in queue interrupt context
+ * or another thread context in order to avoid blocking of the thread forever.
+ *
+ * @param dev
+ * The Unikraft Block Device
+ * @param queue_id
+ * queue_id
+ * @param op
+ * Type of operation
+ * @param sector
+ * Start Sector
+ * @param nb_sectors
+ * Number of sectors
+ * @param buf
+ * Buffer where data is found
+ * @return
+ * - 0: Success
+ * - (<0): on error returned by driver
+ */
+int uk_blkdev_sync_io(struct uk_blkdev *dev,
+ uint16_t queue_id,
+ enum uk_blkreq_op op,
+ __sector sector,
+ __sector nb_sectors,
+ void *buf);
+
+/*
+ * Wrappers for uk_blkdev_sync_io
+ */
+#define uk_blkdev_sync_write(blkdev,\
+ queue_id, \
+ sector, \
+ nb_sectors, \
+ buf) \
+ uk_blkdev_sync_io(blkdev, queue_id, UK_BLKDEV_WRITE, sector, \
+ nb_sectors, buf) \
+
+#define uk_blkdev_sync_read(blkdev,\
+ queue_id, \
+ sector, \
+ nb_sectors, \
+ buf) \
+ uk_blkdev_sync_io(blkdev, queue_id, UK_BLKDEV_READ, sector, \
+ nb_sectors, buf) \
+
+#endif
+
#ifdef __cplusplus
}
#endif
diff --git a/lib/ukblkdev/include/uk/blkdev_core.h
b/lib/ukblkdev/include/uk/blkdev_core.h
index 13cd44ba..8bf08cdd 100644
--- a/lib/ukblkdev/include/uk/blkdev_core.h
+++ b/lib/ukblkdev/include/uk/blkdev_core.h
@@ -39,7 +39,8 @@
#include <uk/list.h>
#include <uk/config.h>
#include <uk/blkreq.h>
-#if defined(CONFIG_LIBUKBLKDEV_DISPATCHERTHREADS)
+#if defined(CONFIG_LIBUKBLKDEV_DISPATCHERTHREADS) || \
+ defined(CONFIG_LIBUKBLKDEV_SYNC_IO_BLOCKED_WAITING)
#include <uk/sched.h>
#include <uk/semaphore.h>
#endif
diff --git a/lib/ukblkdev/include/uk/blkreq.h b/lib/ukblkdev/include/uk/blkreq.h
index aa2cf9c4..8d499cf6 100644
--- a/lib/ukblkdev/include/uk/blkreq.h
+++ b/lib/ukblkdev/include/uk/blkreq.h
@@ -105,6 +105,42 @@ struct uk_blkreq {
};
+/**
+ * Initializes a request structure.
+ *
+ * @param req
+ * The request structure
+ * @param op
+ * The operation
+ * @param start
+ * The start sector
+ * @param nb_sectors
+ * Number of sectors
+ * @param cb
+ * Request callback
+ * @param cb_cookie
+ * Request callback parameters
+ * @param aio_buf
+ * Data buffer
+ **/
+static inline void uk_blkreq_init(struct uk_blkreq *req,
+ enum uk_blkreq_op op, __sector start, __sector nb_sectors,
+ uk_blkreq_event_t cb, void *cb_cookie, void *aio_buf)
+{
+ req->operation = op;
+ req->start_sector = start;
+ req->nb_sectors = nb_sectors;
+ uk_refcount_init(&req->state, UK_BLKDEV_REQ_UNFINISHED);
Hum, I think you are not using this as a reference counter, so I would
use the functions from `<uk/arch/atomic.h>` instead (not <uk/refcount.h>).
ukarch_store_n(&req->state.counter, UK_BLKDEV_REQ_UNFINISHED);
Please also make sure you include the correct header.
Note that I noticed that the atomics API is a bit brokwn, this is why
you need to handover the field for now.
+ req->cb = cb;
+ req->cb_cookie = cb_cookie;
+ req->aio_buf = aio_buf;
+}
+
+/**
+ * Check if request is finished.
+ **/
+#define uk_blkreq_is_done(req) ((req)->state == UK_BLKDEV_REQ_FINISHED)
I think you should use ukarch_load_n():
#define uk_blkreq_is_done(req) \
(ukarch_load_n(&(req)->state.counter) == UK_BLKDEV_REQ_FINISHED)
Could you also provide a helper for drivers to blkdev_driver.h?:
#define uk_blkreq_finished(req) \
(ukarch_store_n(&(req)->state.counter, UK_BLKDEV_REQ_FINISHED)
+
#ifdef __cplusplus
}
#endif
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