Prepare for multithreading of rumpdisk by protecting critical paths
from concurrent access.
TESTED to still boot via rump with this change even though multithread
is not yet enabled.
---
rumpdisk/block-rump.c | 63 ++++++++++++++++++++++++++++++++++++-------
1 file changed, 53 insertions(+), 10 deletions(-)
diff --git a/rumpdisk/block-rump.c b/rumpdisk/block-rump.c
index 10fa66ad..03731b36 100644
--- a/rumpdisk/block-rump.c
+++ b/rumpdisk/block-rump.c
@@ -52,6 +52,9 @@ static bool disabled;
static mach_port_t master_host;
+/* Lock to protect concurrent multithread access */
+pthread_mutex_t rumpdisk_rwlock = PTHREAD_MUTEX_INITIALIZER;
+
/* One of these is associated with each open instance of a device. */
struct block_data
{
@@ -183,16 +186,26 @@ rumpdisk_device_close (void *d)
struct block_data *bd = d;
io_return_t err;
+ pthread_mutex_lock (&rumpdisk_rwlock);
+
bd->taken--;
if (bd->taken)
- return D_SUCCESS;
+ {
+ pthread_mutex_unlock (&rumpdisk_rwlock);
+ return D_SUCCESS;
+ }
err = rump_errno2host (rump_sys_close (bd->rump_fd));
if (err != D_SUCCESS)
- return err;
+ {
+ pthread_mutex_unlock (&rumpdisk_rwlock);
+ return err;
+ }
ports_port_deref (bd);
ports_destroy_right (bd);
+
+ pthread_mutex_unlock (&rumpdisk_rwlock);
return D_SUCCESS;
}
@@ -233,22 +246,32 @@ rumpdisk_device_open (mach_port_t reply_port,
mach_msg_type_name_t reply_port_ty
bd = search_bd (name);
if (bd)
{
+ pthread_mutex_lock (&rumpdisk_rwlock);
+
bd->taken++;
*devp = ports_get_right (bd);
*devicePoly = MACH_MSG_TYPE_MAKE_SEND;
+
+ pthread_mutex_unlock (&rumpdisk_rwlock);
return D_SUCCESS;
}
translate_name (dev_name, DISK_NAME_LEN, name);
+ pthread_mutex_lock(&rumpdisk_rwlock);
+
fd = rump_sys_open (dev_name, dev_mode_to_rump_mode (mode));
if (fd < 0)
- return rump_errno2host (errno);
+ {
+ pthread_mutex_unlock (&rumpdisk_rwlock);
+ return rump_errno2host (errno);
+ }
ret = rump_sys_ioctl (fd, DIOCGMEDIASIZE, &media_size);
if (ret < 0)
{
mach_print ("DIOCGMEDIASIZE ioctl fails\n");
+ pthread_mutex_unlock (&rumpdisk_rwlock);
return rump_errno2host (errno);
}
@@ -256,6 +279,7 @@ rumpdisk_device_open (mach_port_t reply_port,
mach_msg_type_name_t reply_port_ty
if (ret < 0)
{
mach_print ("DIOCGSECTORSIZE ioctl fails\n");
+ pthread_mutex_unlock (&rumpdisk_rwlock);
return rump_errno2host (errno);
}
@@ -263,6 +287,7 @@ rumpdisk_device_open (mach_port_t reply_port,
mach_msg_type_name_t reply_port_ty
if (err != 0)
{
rump_sys_close (fd);
+ pthread_mutex_unlock (&rumpdisk_rwlock);
return err;
}
@@ -280,6 +305,8 @@ rumpdisk_device_open (mach_port_t reply_port,
mach_msg_type_name_t reply_port_ty
*devp = ports_get_right (bd);
*devicePoly = MACH_MSG_TYPE_MAKE_SEND;
+
+ pthread_mutex_unlock (&rumpdisk_rwlock);
return D_SUCCESS;
}
@@ -296,6 +323,8 @@ rumpdisk_device_write (void *d, mach_port_t reply_port,
if ((bd->mode & D_WRITE) == 0)
return D_INVALID_OPERATION;
+ pthread_mutex_lock (&rumpdisk_rwlock);
+
if ((vm_offset_t) data % pagesize)
{
/* Not aligned, have to copy to aligned buffer. */
@@ -307,7 +336,10 @@ rumpdisk_device_write (void *d, mach_port_t reply_port,
/* While at it, make it contiguous */
ret = vm_allocate_contiguous (master_host, mach_task_self (), &buf,
&pap, count, 0, 0x100000000ULL, 0);
if (ret != KERN_SUCCESS)
- return ENOMEM;
+ {
+ pthread_mutex_unlock (&rumpdisk_rwlock);
+ return ENOMEM;
+ }
memcpy ((void*) buf, data, count);
@@ -317,7 +349,10 @@ rumpdisk_device_write (void *d, mach_port_t reply_port,
vm_deallocate (mach_task_self (), (vm_address_t) buf, count);
if (written < 0)
- return rump_errno2host (err);
+ {
+ pthread_mutex_unlock (&rumpdisk_rwlock);
+ return rump_errno2host (err);
+ }
}
else
{
@@ -343,7 +378,10 @@ rumpdisk_device_write (void *d, mach_port_t reply_port,
done = rump_sys_pwrite (bd->rump_fd, (const void *)data + written,
todo, (off_t)bn * bd->block_size + written);
if (done < 0)
- return rump_errno2host (errno);
+ {
+ pthread_mutex_unlock (&rumpdisk_rwlock);
+ return rump_errno2host (errno);
+ }
written += done;
}
@@ -352,6 +390,7 @@ rumpdisk_device_write (void *d, mach_port_t reply_port,
vm_deallocate (mach_task_self (), (vm_address_t) data, count);
*bytes_written = (int)written;
+ pthread_mutex_unlock (&rumpdisk_rwlock);
return D_SUCCESS;
}
@@ -375,11 +414,16 @@ rumpdisk_device_read (void *d, mach_port_t reply_port,
if (count == 0)
return D_SUCCESS;
+ pthread_mutex_lock (&rumpdisk_rwlock);
+
/* TODO: directly write at *data when it is aligned */
*data = 0;
ret = vm_allocate (mach_task_self (), &buf, npages * pagesize, TRUE);
if (ret != KERN_SUCCESS)
- return ENOMEM;
+ {
+ pthread_mutex_unlock (&rumpdisk_rwlock);
+ return ENOMEM;
+ }
/* Ensure physical allocation by writing a single byte of each */
for (i = 0; i < npages; i++)
@@ -400,6 +444,7 @@ rumpdisk_device_read (void *d, mach_port_t reply_port,
{
err = errno;
vm_deallocate (mach_task_self (), buf, npages * pagesize);
+ pthread_mutex_unlock (&rumpdisk_rwlock);
return rump_errno2host (err);
}
@@ -408,6 +453,7 @@ rumpdisk_device_read (void *d, mach_port_t reply_port,
*bytes_read = done;
*data = (void*) buf;
+ pthread_mutex_unlock (&rumpdisk_rwlock);
return D_SUCCESS;
}
@@ -455,9 +501,6 @@ rumpdisk_device_get_status (void *d, dev_flavor_t flavor,
dev_status_t status,
* Short term strategy:
*
* Make device_read/write multithreaded.
- * Note: this would require an rwlock between device_open/close/read/write, to
- * protect against e.g. concurrent open, unexpected close while read/write is
- * called, etc.
*
* Long term strategy:
*
--
2.35.1
