hrev56161 adds 1 changeset to branch 'master'
old head: 25742b78fb8de17c76b0c8dfefa34441c9a88e95
new head: c146183167273258c790ed24e6fa6b26c8fd8bbf
overview:
https://git.haiku-os.org/haiku/log/?qt=range&q=c14618316727+%5E25742b78fb8d
----------------------------------------------------------------------------
c14618316727: devfs: Do not perform synchronous requests in devfs_io.
In some circumstances, we can wind up iterating on requests
by recursing through this function once per "iteration" due to
how vfs_synchronous_io works. This can run out of stack, as
was seen in #9900 and potentially other tickets.
An initial attempt was made to fix the problem in hrev45906,
but it was quickly reverted because it seems to have broken
I/O for all devices that do not support the "IO" hook.
This solution is much simpler: the VFS layer already can handle
vnodes' IO hooks returning B_UNSUPPORTED and then falling back
to synchronous I/O just as if they had no IO hook at all.
This should hopefully cause iteration to occur without recursion.
Tested by booting off a USB drive (the usb_disk driver does not
support the IO hook, so all requests must be translated.)
May fix #9900.
[ Augustin Cavalier <waddlesplash@xxxxxxxxx> ]
----------------------------------------------------------------------------
Revision: hrev56161
Commit: c146183167273258c790ed24e6fa6b26c8fd8bbf
URL: https://git.haiku-os.org/haiku/commit/?id=c14618316727
Author: Augustin Cavalier <waddlesplash@xxxxxxxxx>
Date: Tue Jun 7 18:30:21 2022 UTC
Ticket: https://dev.haiku-os.org/ticket/9900
----------------------------------------------------------------------------
1 file changed, 5 insertions(+), 38 deletions(-)
src/system/kernel/device_manager/devfs.cpp | 43 +++-----------------------
----------------------------------------------------------------------------
diff --git a/src/system/kernel/device_manager/devfs.cpp
b/src/system/kernel/device_manager/devfs.cpp
index 0cf66faaa0..66c41a5555 100644
--- a/src/system/kernel/device_manager/devfs.cpp
+++ b/src/system/kernel/device_manager/devfs.cpp
@@ -149,11 +149,6 @@ struct devfs_cookie {
void* device_cookie;
};
-struct synchronous_io_cookie {
- BaseDevice* device;
- void* cookie;
-};
-
// directory iteration states
enum {
ITERATION_STATE_DOT = 0,
@@ -818,22 +813,6 @@ get_device_name(struct devfs_vnode* vnode, char* buffer,
size_t size)
}
-static status_t
-device_read(void* _cookie, off_t offset, void* buffer, size_t* length)
-{
- synchronous_io_cookie* cookie = (synchronous_io_cookie*)_cookie;
- return cookie->device->Read(cookie->cookie, offset, buffer, length);
-}
-
-
-static status_t
-device_write(void* _cookie, off_t offset, void* buffer, size_t* length)
-{
- synchronous_io_cookie* cookie = (synchronous_io_cookie*)_cookie;
- return cookie->device->Write(cookie->cookie, offset, buffer, length);
-}
-
-
static int
dump_node(int argc, char** argv)
{
@@ -1828,17 +1807,14 @@ devfs_io(fs_volume* volume, fs_vnode* _vnode, void*
_cookie,
devfs_vnode* vnode = (devfs_vnode*)_vnode->private_node;
devfs_cookie* cookie = (devfs_cookie*)_cookie;
- bool isWrite = request->IsWrite();
-
- if (!S_ISCHR(vnode->stream.type)
- || (((isWrite && !vnode->stream.u.dev.device->HasWrite())
- || (!isWrite &&
!vnode->stream.u.dev.device->HasRead()))
- && !vnode->stream.u.dev.device->HasIO())
- || cookie == NULL) {
+ if (!S_ISCHR(vnode->stream.type) || cookie == NULL) {
request->SetStatusAndNotify(B_NOT_ALLOWED);
return B_NOT_ALLOWED;
}
+ if (!vnode->stream.u.dev.device->HasIO())
+ return B_UNSUPPORTED;
+
if (vnode->stream.u.dev.partition != NULL) {
if (request->Offset() + (off_t)request->Length()
> vnode->stream.u.dev.partition->info.size) {
@@ -1848,16 +1824,7 @@ devfs_io(fs_volume* volume, fs_vnode* _vnode, void*
_cookie,
translate_partition_access(vnode->stream.u.dev.partition,
request);
}
- if (vnode->stream.u.dev.device->HasIO())
- return vnode->stream.u.dev.device->IO(cookie->device_cookie,
request);
-
- synchronous_io_cookie synchronousCookie = {
- vnode->stream.u.dev.device,
- cookie->device_cookie
- };
-
- return vfs_synchronous_io(request,
- request->IsWrite() ? &device_write : &device_read,
&synchronousCookie);
+ return vnode->stream.u.dev.device->IO(cookie->device_cookie, request);
}
