[Qemu-devel] [PATCH 1/3] ide: factor dma handling helpers

[Qemu-devel] [PATCH 1/3] ide: factor dma handling helpers

[Christoph Hellwig]

Factor the DMA I/O path that is duplicated between read and write
commands, into common helpers using the s->is_read flag added for
the macio ATA controller.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: qemu/hw/ide/core.c
===================================================================
--- qemu.orig/hw/ide/core.c	2010-12-17 11:38:48.992003425 +0100
+++ qemu/hw/ide/core.c	2010-12-17 11:48:43.252255415 +0100
@@ -487,16 +487,18 @@ static int ide_handle_rw_error(IDEState
     return 1;
 }
 
-void ide_read_dma_cb(void *opaque, int ret)
+void ide_dma_cb(void *opaque, int ret)
 {
     IDEState *s = opaque;
     int n;
     int64_t sector_num;
 
     if (ret < 0) {
-        if (ide_handle_rw_error(s, -ret,
-            BM_STATUS_DMA_RETRY | BM_STATUS_RETRY_READ))
-        {
+        int op = BM_STATUS_DMA_RETRY;
+
+        if (s->is_read)
+            op |= BM_STATUS_RETRY_READ;
+        if (ide_handle_rw_error(s, -ret, op)) {
             return;
         }
     }
@@ -504,7 +506,7 @@ void ide_read_dma_cb(void *opaque, int r
     n = s->io_buffer_size >> 9;
     sector_num = ide_get_sector(s);
     if (n > 0) {
-        dma_buf_commit(s, 1);
+        dma_buf_commit(s, s->is_read);
         sector_num += n;
         ide_set_sector(s, sector_num);
         s->nsector -= n;
@@ -514,32 +516,44 @@ void ide_read_dma_cb(void *opaque, int r
     if (s->nsector == 0) {
         s->status = READY_STAT | SEEK_STAT;
         ide_set_irq(s->bus);
-    eot:
-        s->bus->dma->ops->add_status(s->bus->dma, BM_STATUS_INT);
-        ide_set_inactive(s);
-        return;
+        goto eot;
     }
 
     /* launch next transfer */
     n = s->nsector;
-    s->io_buffer_index = 0;
+    if (s->is_read)
+        s->io_buffer_index = 0;
     s->io_buffer_size = n * 512;
-    if (s->bus->dma->ops->prepare_buf(s->bus->dma, 1) == 0)
+    if (s->bus->dma->ops->prepare_buf(s->bus->dma, s->is_read) == 0)
         goto eot;
+
 #ifdef DEBUG_AIO
-    printf("aio_read: sector_num=%" PRId64 " n=%d\n", sector_num, n);
+    printf("ide_dma_cb: sector_num=%" PRId64 " n=%d, is_read=%d\n",
+           sector_num, n, s->is_read);
 #endif
-    s->bus->dma->aiocb = dma_bdrv_read(s->bs, &s->sg, sector_num, ide_read_dma_cb, s);
-    ide_dma_submit_check(s, ide_read_dma_cb);
+
+    if (s->is_read) {
+        s->bus->dma->aiocb = dma_bdrv_read(s->bs, &s->sg, sector_num,
+                                           ide_dma_cb, s);
+    } else {
+        s->bus->dma->aiocb = dma_bdrv_write(s->bs, &s->sg, sector_num,
+                                            ide_dma_cb, s);
+    }
+    ide_dma_submit_check(s, ide_dma_cb);
+    return;
+
+eot:
+   s->bus->dma->ops->add_status(s->bus->dma, BM_STATUS_INT);
+   ide_set_inactive(s);
 }
 
-static void ide_sector_read_dma(IDEState *s)
+static void ide_sector_start_dma(IDEState *s, int is_read)
 {
     s->status = READY_STAT | SEEK_STAT | DRQ_STAT | BUSY_STAT;
     s->io_buffer_index = 0;
     s->io_buffer_size = 0;
-    s->is_read = 1;
-    s->bus->dma->ops->start_dma(s->bus->dma, s, ide_read_dma_cb);
+    s->is_read = is_read;
+    s->bus->dma->ops->start_dma(s->bus->dma, s, ide_dma_cb);
 }
 
 static void ide_sector_write_timer_cb(void *opaque)
@@ -594,57 +608,6 @@ void ide_sector_write(IDEState *s)
     }
 }
 
-void ide_write_dma_cb(void *opaque, int ret)
-{
-    IDEState *s = opaque;
-    int n;
-    int64_t sector_num;
-
-    if (ret < 0) {
-        if (ide_handle_rw_error(s, -ret,  BM_STATUS_DMA_RETRY))
-            return;
-    }
-
-    n = s->io_buffer_size >> 9;
-    sector_num = ide_get_sector(s);
-    if (n > 0) {
-        dma_buf_commit(s, 0);
-        sector_num += n;
-        ide_set_sector(s, sector_num);
-        s->nsector -= n;
-    }
-
-    /* end of transfer ? */
-    if (s->nsector == 0) {
-        s->status = READY_STAT | SEEK_STAT;
-        ide_set_irq(s->bus);
-    eot:
-        s->bus->dma->ops->add_status(s->bus->dma, BM_STATUS_INT);
-        ide_set_inactive(s);
-        return;
-    }
-
-    n = s->nsector;
-    s->io_buffer_size = n * 512;
-    /* launch next transfer */
-    if (s->bus->dma->ops->prepare_buf(s->bus->dma, 0) == 0)
-        goto eot;
-#ifdef DEBUG_AIO
-    printf("aio_write: sector_num=%" PRId64 " n=%d\n", sector_num, n);
-#endif
-    s->bus->dma->aiocb = dma_bdrv_write(s->bs, &s->sg, sector_num, ide_write_dma_cb, s);
-    ide_dma_submit_check(s, ide_write_dma_cb);
-}
-
-static void ide_sector_write_dma(IDEState *s)
-{
-    s->status = READY_STAT | SEEK_STAT | DRQ_STAT | BUSY_STAT;
-    s->io_buffer_index = 0;
-    s->io_buffer_size = 0;
-    s->is_read = 0;
-    s->bus->dma->ops->start_dma(s->bus->dma, s, ide_write_dma_cb);
-}
-
 void ide_atapi_cmd_ok(IDEState *s)
 {
     s->error = 0;
@@ -1858,7 +1821,7 @@ void ide_exec_cmd(IDEBus *bus, uint32_t
         if (!s->bs)
             goto abort_cmd;
 	ide_cmd_lba48_transform(s, lba48);
-        ide_sector_read_dma(s);
+        ide_sector_start_dma(s, 1);
         break;
 	case WIN_WRITEDMA_EXT:
 	lba48 = 1;
@@ -1867,7 +1830,7 @@ void ide_exec_cmd(IDEBus *bus, uint32_t
         if (!s->bs)
             goto abort_cmd;
 	ide_cmd_lba48_transform(s, lba48);
-        ide_sector_write_dma(s);
+        ide_sector_start_dma(s, 0);
         s->media_changed = 1;
         break;
     case WIN_READ_NATIVE_MAX_EXT:
Index: qemu/hw/ide/internal.h
===================================================================
--- qemu.orig/hw/ide/internal.h	2010-12-17 11:42:29.538004334 +0100
+++ qemu/hw/ide/internal.h	2010-12-17 11:48:05.464261142 +0100
@@ -439,7 +439,6 @@ struct IDEState {
     uint32_t mdata_size;
     uint8_t *mdata_storage;
     int media_changed;
-    /* for pmac */
     int is_read;
     /* SMART */
     uint8_t smart_enabled;
@@ -560,8 +559,7 @@ void ide_init2_with_non_qdev_drives(IDEB
 void ide_init_ioport(IDEBus *bus, int iobase, int iobase2);
 
 void ide_exec_cmd(IDEBus *bus, uint32_t val);
-void ide_read_dma_cb(void *opaque, int ret);
-void ide_write_dma_cb(void *opaque, int ret);
+void ide_dma_cb(void *opaque, int ret);
 void ide_sector_write(IDEState *s);
 void ide_sector_read(IDEState *s);
 void ide_flush_cache(IDEState *s);
Index: qemu/hw/ide/pci.c
===================================================================
--- qemu.orig/hw/ide/pci.c	2010-12-17 11:42:03.440254508 +0100
+++ qemu/hw/ide/pci.c	2010-12-17 11:42:23.998252692 +0100
@@ -178,14 +178,9 @@ static void bmdma_restart_dma(BMDMAState
     s->io_buffer_index = 0;
     s->io_buffer_size = 0;
     s->nsector = bm->nsector;
+    s->is_read = is_read;
     bm->cur_addr = bm->addr;
-
-    if (is_read) {
-        bm->dma_cb = ide_read_dma_cb;
-    } else {
-        bm->dma_cb = ide_write_dma_cb;
-    }
-
+    bm->dma_cb = ide_dma_cb;
     bmdma_start_dma(&bm->dma, s, bm->dma_cb);
 }
 

[Qemu-devel] [PATCH 2/3] ide: also reset io_buffer_index for writes

[Christoph Hellwig]

Currenly the code only resets the io_buffer_index field for reads,
but the code seems to expect this for all types of I/O.  I guess
we simply don't hit large enough transfers that would require this
often enough.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: qemu/hw/ide/core.c
===================================================================
--- qemu.orig/hw/ide/core.c	2010-12-17 12:03:27.737004194 +0100
+++ qemu/hw/ide/core.c	2010-12-17 12:03:41.485004404 +0100
@@ -521,8 +521,7 @@ void ide_dma_cb(void *opaque, int ret)
 
     /* launch next transfer */
     n = s->nsector;
-    if (s->is_read)
-        s->io_buffer_index = 0;
+    s->io_buffer_index = 0;
     s->io_buffer_size = n * 512;
     if (s->bus->dma->ops->prepare_buf(s->bus->dma, s->is_read) == 0)
         goto eot;

[Qemu-devel] [PATCH 3/3] ide: kill ide_dma_submit_check

[Christoph Hellwig]

Merge ide_dma_submit_check into it's only caller.  Also use tail recursion
using a goto instead of a real recursion - this avoid overflowing the
stack in the pathological situation of an recurring error that is ignored.
We'll still be busy looping in ide_dma_cb, but at least won't eat up
all stack space after this.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: qemu/hw/ide/core.c
===================================================================
--- qemu.orig/hw/ide/core.c	2010-12-20 13:16:11.379004054 +0100
+++ qemu/hw/ide/core.c	2010-12-20 13:16:11.000000000 +0100
@@ -321,14 +321,6 @@ static inline void ide_abort_command(IDE
     s->error = ABRT_ERR;
 }
 
-static inline void ide_dma_submit_check(IDEState *s,
-          BlockDriverCompletionFunc *dma_cb)
-{
-    if (s->bus->dma->aiocb)
-	return;
-    dma_cb(s, -1);
-}
-
 /* prepare data transfer and tell what to do after */
 static void ide_transfer_start(IDEState *s, uint8_t *buf, int size,
                                EndTransferFunc *end_transfer_func)
@@ -493,6 +485,7 @@ void ide_dma_cb(void *opaque, int ret)
     int n;
     int64_t sector_num;
 
+handle_rw_error:
     if (ret < 0) {
         int op = BM_STATUS_DMA_RETRY;
 
@@ -538,7 +531,11 @@ void ide_dma_cb(void *opaque, int ret)
         s->bus->dma->aiocb = dma_bdrv_write(s->bs, &s->sg, sector_num,
                                             ide_dma_cb, s);
     }
-    ide_dma_submit_check(s, ide_dma_cb);
+
+    if (!s->bus->dma->aiocb) {
+        ret = -1;
+        goto handle_rw_error;
+    }
     return;
 
 eot:

Re: [Qemu-devel] [PATCH 1/3] ide: factor dma handling helpers

[Kevin Wolf]

Am 20.12.2010 13:45, schrieb Christoph Hellwig:
> Factor the DMA I/O path that is duplicated between read and write
> commands, into common helpers using the s->is_read flag added for
> the macio ATA controller.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Thanks, applied all to the block branch.

Kevin