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[Qemu-devel] [PATCH 5/5] ide: introduce ide_transfer_start_norecurse
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 5/5] ide: introduce ide_transfer_start_norecurse |
Date: |
Fri, 23 Feb 2018 16:26:40 +0100 |
For the case where the end_transfer_func is also the caller of
ide_transfer_start, the mutual recursion can lead to unlimited
stack usage. Introduce a new version that can be used to change
tail recursion into a loop, and use it in trace_ide_atapi_cmd_reply_end.
Signed-off-by: Paolo Bonzini <address@hidden>
---
hw/ide/atapi.c | 35 +++++++++++++++++++----------------
hw/ide/core.c | 16 ++++++++++++----
include/hw/ide/internal.h | 2 ++
3 files changed, 33 insertions(+), 20 deletions(-)
diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
index be99a929cf..4df4a66bbe 100644
--- a/hw/ide/atapi.c
+++ b/hw/ide/atapi.c
@@ -248,12 +248,7 @@ void ide_atapi_cmd_reply_end(IDEState *s)
trace_ide_atapi_cmd_reply_end(s, s->packet_transfer_size,
s->elementary_transfer_size,
s->io_buffer_index);
- if (s->packet_transfer_size <= 0) {
- /* end of transfer */
- ide_atapi_cmd_ok(s);
- ide_set_irq(s->bus);
- trace_ide_atapi_cmd_reply_end_eot(s, s->status);
- } else {
+ while (s->packet_transfer_size > 0) {
/* see if a new sector must be read */
if (s->lba != -1 && s->io_buffer_index >= s->cd_sector_size) {
if (!s->elementary_transfer_size) {
@@ -279,11 +274,6 @@ void ide_atapi_cmd_reply_end(IDEState *s)
size = s->cd_sector_size - s->io_buffer_index;
if (size > s->elementary_transfer_size)
size = s->elementary_transfer_size;
- s->packet_transfer_size -= size;
- s->elementary_transfer_size -= size;
- s->io_buffer_index += size;
- ide_transfer_start(s, s->io_buffer + s->io_buffer_index - size,
- size, ide_atapi_cmd_reply_end);
} else {
/* a new transfer is needed */
s->nsector = (s->nsector & ~7) | ATAPI_INT_REASON_IO;
@@ -305,14 +295,27 @@ void ide_atapi_cmd_reply_end(IDEState *s)
if (size > (s->cd_sector_size - s->io_buffer_index))
size = (s->cd_sector_size - s->io_buffer_index);
}
- s->packet_transfer_size -= size;
- s->elementary_transfer_size -= size;
- s->io_buffer_index += size;
trace_ide_atapi_cmd_reply_end_new(s, s->status);
- ide_transfer_start(s, s->io_buffer + s->io_buffer_index - size,
- size, ide_atapi_cmd_reply_end);
+ }
+ s->packet_transfer_size -= size;
+ s->elementary_transfer_size -= size;
+ s->io_buffer_index += size;
+
+ /* Some adapters process PIO data right away. In that case, we need
+ * to avoid mutual recursion between ide_transfer_start
+ * and ide_atapi_cmd_reply_end.
+ */
+ if (!ide_transfer_start_norecurse(s,
+ s->io_buffer + s->io_buffer_index -
size,
+ size, ide_atapi_cmd_reply_end)) {
+ return;
}
}
+
+ /* end of transfer */
+ ide_atapi_cmd_ok(s);
+ ide_set_irq(s->bus);
+ trace_ide_atapi_cmd_reply_end_eot(s, s->status);
}
/* send a reply of 'size' bytes in s->io_buffer to an ATAPI command */
diff --git a/hw/ide/core.c b/hw/ide/core.c
index 447d9624df..ddefeb086d 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -529,8 +529,8 @@ static void ide_clear_retry(IDEState *s)
}
/* prepare data transfer and tell what to do after */
-void ide_transfer_start(IDEState *s, uint8_t *buf, int size,
- EndTransferFunc *end_transfer_func)
+bool ide_transfer_start_norecurse(IDEState *s, uint8_t *buf, int size,
+ EndTransferFunc *end_transfer_func)
{
s->data_ptr = buf;
s->data_end = buf + size;
@@ -540,10 +540,18 @@ void ide_transfer_start(IDEState *s, uint8_t *buf, int
size,
}
if (!s->bus->dma->ops->start_transfer) {
s->end_transfer_func = end_transfer_func;
- return;
+ return false;
}
s->bus->dma->ops->start_transfer(s->bus->dma);
- end_transfer_func(s);
+ return true;
+}
+
+void ide_transfer_start(IDEState *s, uint8_t *buf, int size,
+ EndTransferFunc *end_transfer_func)
+{
+ if (ide_transfer_start_norecurse(s, buf, size, end_transfer_func)) {
+ end_transfer_func(s);
+ }
}
static void ide_cmd_done(IDEState *s)
diff --git a/include/hw/ide/internal.h b/include/hw/ide/internal.h
index efaabbd815..1bd93d0a30 100644
--- a/include/hw/ide/internal.h
+++ b/include/hw/ide/internal.h
@@ -624,6 +624,8 @@ void ide_exec_cmd(IDEBus *bus, uint32_t val);
void ide_transfer_start(IDEState *s, uint8_t *buf, int size,
EndTransferFunc *end_transfer_func);
+bool ide_transfer_start_norecurse(IDEState *s, uint8_t *buf, int size,
+ EndTransferFunc *end_transfer_func);
void ide_transfer_stop(IDEState *s);
void ide_set_inactive(IDEState *s, bool more);
BlockAIOCB *ide_issue_trim(
--
2.14.3
- [Qemu-devel] [RFC PATCH 0/5] atapi: change unlimited recursion to while loop, Paolo Bonzini, 2018/02/23
- [Qemu-devel] [PATCH 3/5] ide: do not set s->end_transfer_func to ide_transfer_cancel, Paolo Bonzini, 2018/02/23
- [Qemu-devel] [PATCH 4/5] atapi: call ide_set_irq before ide_transfer_start, Paolo Bonzini, 2018/02/23
- [Qemu-devel] [PATCH 2/5] ide: push end_transfer callback to ide_transfer_halt, Paolo Bonzini, 2018/02/23
- [Qemu-devel] [PATCH 1/5] ide: push call to end_transfer_func out of start_transfer callback, Paolo Bonzini, 2018/02/23
- [Qemu-devel] [PATCH 5/5] ide: introduce ide_transfer_start_norecurse,
Paolo Bonzini <=
- Re: [Qemu-devel] [RFC PATCH 0/5] atapi: change unlimited recursion to while loop, John Snow, 2018/02/27