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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v2 03/29] tools/xenlogd: connect to frontend
Add the code for connecting to frontends to xenlogd.
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V2:
- support multiple rings per device (Jason Andryuk)
- don't set .revents initially (Jason Andryuk)
- call poll() with infinite timeout (Jason Andryuk)
- take mutex before calling pthread_cond_signal()
---
tools/xen-9pfsd/Makefile | 2 +-
tools/xen-9pfsd/io.c | 45 +++
tools/xen-9pfsd/xen-9pfsd.c | 625 +++++++++++++++++++++++++++++++++++-
tools/xen-9pfsd/xen-9pfsd.h | 60 ++++
4 files changed, 728 insertions(+), 4 deletions(-)
create mode 100644 tools/xen-9pfsd/io.c
create mode 100644 tools/xen-9pfsd/xen-9pfsd.h
diff --git a/tools/xen-9pfsd/Makefile b/tools/xen-9pfsd/Makefile
index 4e35202f08..2023b19c62 100644
--- a/tools/xen-9pfsd/Makefile
+++ b/tools/xen-9pfsd/Makefile
@@ -10,7 +10,7 @@ LDFLAGS += $(PTHREAD_LDFLAGS)
TARGETS := xen-9pfsd
-XEN-9PFSD_OBJS = xen-9pfsd.o
+XEN-9PFSD_OBJS = xen-9pfsd.o io.o
$(XEN-9PFSD_OBJS): CFLAGS += $(CFLAGS_libxenstore)
$(XEN-9PFSD_OBJS): CFLAGS += $(CFLAGS_libxenevtchn)
$(XEN-9PFSD_OBJS): CFLAGS += $(CFLAGS_libxengnttab)
diff --git a/tools/xen-9pfsd/io.c b/tools/xen-9pfsd/io.c
new file mode 100644
index 0000000000..e1e37970f4
--- /dev/null
+++ b/tools/xen-9pfsd/io.c
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * xen-9pfsd - Xen 9pfs daemon
+ *
+ * Copyright (C) 2023 Juergen Gross <jgross@xxxxxxxx>
+ *
+ * I/O thread handling.
+ */
+
+#include <stdbool.h>
+#include <string.h>
+#include <syslog.h>
+
+#include "xen-9pfsd.h"
+
+static bool io_work_pending(struct ring *ring)
+{
+ if ( ring->stop_thread )
+ return true;
+ return false;
+}
+
+void *io_thread(void *arg)
+{
+ struct ring *ring = arg;
+
+ while ( !ring->stop_thread )
+ {
+ pthread_mutex_lock(&ring->mutex);
+ if ( !io_work_pending(ring) )
+ {
+ if ( xenevtchn_unmask(xe, ring->evtchn) < 0 )
+ syslog(LOG_WARNING, "xenevtchn_unmask() failed");
+ pthread_cond_wait(&ring->cond, &ring->mutex);
+ }
+ pthread_mutex_unlock(&ring->mutex);
+
+ /* TODO: I/O handling. */
+ }
+
+ ring->thread_active = false;
+
+ return NULL;
+}
diff --git a/tools/xen-9pfsd/xen-9pfsd.c b/tools/xen-9pfsd/xen-9pfsd.c
index c365b35fe5..cc5734402d 100644
--- a/tools/xen-9pfsd/xen-9pfsd.c
+++ b/tools/xen-9pfsd/xen-9pfsd.c
@@ -24,34 +24,604 @@
#include <err.h>
#include <errno.h>
+#include <poll.h>
+#include <pthread.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
+#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
-#include <xenevtchn.h>
#include <xengnttab.h>
#include <xenstore.h>
+#include "xen-9pfsd.h"
+
+/*
+ * List of currently known devices.
+ * The list itself is modified only in the main thread. When a device is being
+ * removed its memory needs to be freed after the I/O thread (if existing)
+ * has stopped.
+ */
+static XEN_TAILQ_HEAD(devhead, device) devs = XEN_TAILQ_HEAD_INITIALIZER(devs);
+
+struct path {
+ char path[100];
+};
+
static volatile bool stop_me;
static bool daemon_running;
static struct xs_handle *xs;
static xengnttab_handle *xg;
-static xenevtchn_handle *xe;
+static unsigned int now;
+
+xenevtchn_handle *xe;
static void handle_stop(int sig)
{
stop_me = true;
}
+static int check_host_path(device *device)
+{
+ struct stat statbuf;
+ char *path, *p;
+ int ret = 1;
+
+ if ( !device->host_path )
+ return 1;
+
+ if ( device->host_path[0] != '/' )
+ return 1;
+
+ path = strdup(device->host_path);
+ if ( !path )
+ {
+ syslog(LOG_CRIT, "memory allocation failure!");
+ return 1;
+ }
+
+ for ( p = path; p; )
+ {
+ p = strchr(p + 1, '/');
+ if ( p )
+ *p = 0;
+ if ( !stat(path, &statbuf) )
+ {
+ if ( !(statbuf.st_mode & S_IFDIR) )
+ break;
+ if ( !p )
+ {
+ ret = 0;
+ break;
+ }
+ *p = '/';
+ continue;
+ }
+ if ( mkdir(path, 0777) )
+ break;
+ if ( p )
+ *p = '/';
+ }
+
+ free(path);
+ return ret;
+}
+
+static void construct_frontend_path(device *device, const char *node,
+ struct path *p)
+{
+ snprintf(p->path, sizeof(p->path), "/local/domain/%u/device/9pfs/%u/%s",
+ device->domid, device->devid, node);
+}
+
+static void construct_backend_path(device *device, const char *node,
+ struct path *p)
+{
+ snprintf(p->path, sizeof(p->path), "backend/xen_9pfs/%u/%u/%s",
+ device->domid, device->devid, node);
+}
+
+static char *read_backend_node(device *device, const char *node)
+{
+ struct path p;
+ char *val;
+ unsigned int len;
+
+ construct_backend_path(device, node, &p);
+ val = xs_read(xs, XBT_NULL, p.path, &len);
+
+ return val;
+}
+
+static unsigned int uint_from_string(char *string, unsigned int def)
+{
+ unsigned long val;
+ char *end;
+
+ if ( !string )
+ return def;
+
+ val = strtoul(string, &end, 10);
+ if ( *end || val > UINT_MAX )
+ val = def;
+ free(string);
+
+ return val;
+}
+
+static unsigned int read_backend_node_uint(device *device, const char *node,
+ unsigned int def)
+{
+ return uint_from_string(read_backend_node(device, node), def);
+}
+
+static unsigned int read_frontend_node_uint(device *device, const char *node,
+ unsigned int def)
+{
+ struct path p;
+ unsigned int len;
+
+ construct_frontend_path(device, node, &p);
+
+ return uint_from_string(xs_read(xs, XBT_NULL, p.path, &len), def);
+}
+
+static int write_backend_node(device *device, const char *node, const char
*val)
+{
+ struct path p;
+ struct xs_permissions perms[2] = {
+ { .id = 0, .perms = XS_PERM_NONE },
+ { .id = device->domid, .perms = XS_PERM_READ }
+ };
+
+ construct_backend_path(device, node, &p);
+ if ( !xs_write(xs, XBT_NULL, p.path, val, strlen(val)) )
+ {
+ syslog(LOG_ERR, "error writing bacḱend node \"%s\" for device %u/%u",
+ node, device->domid, device->devid);
+ return 1;
+ }
+
+ if ( !xs_set_permissions(xs, XBT_NULL, p.path, perms, 2) )
+ {
+ syslog(LOG_ERR, "error setting permissions for \"%s\"", p.path);
+ return 1;
+ }
+
+ return 0;
+}
+
+static int write_backend_node_uint(device *device, const char *node,
+ unsigned int val)
+{
+ char str[12];
+
+ snprintf(str, sizeof(str), "%u", val);
+
+ return write_backend_node(device, node, str);
+}
+
+static int write_backend_state(device *device, enum xenbus_state state)
+{
+ struct path p;
+ char val[2];
+
+ snprintf(val, sizeof(val), "%u", state);
+ construct_backend_path(device, "state", &p);
+ if ( !xs_write(xs, XBT_NULL, p.path, val, 1) )
+ {
+ syslog(LOG_ERR, "error writing backend state %u for device %u/%u",
+ state, device->domid, device->devid);
+ return 1;
+ }
+
+ device->backend_state = state;
+
+ return 0;
+}
+
+static device *find_device(unsigned int domid, unsigned int devid)
+{
+ device *device;
+
+ XEN_TAILQ_FOREACH( device, &devs, list )
+ {
+ if ( domid == device->domid && devid == device->devid )
+ return device;
+ }
+
+ return NULL;
+}
+
+static void free_device(device *device)
+{
+ char token[20];
+ struct path p;
+
+ construct_frontend_path(device, "state", &p);
+ snprintf(token, sizeof(token), "%u/%u", device->domid, device->devid);
+ xs_unwatch(xs, p.path, token);
+
+ free(device->host_path);
+ free(device);
+}
+
+static device *new_device(unsigned int domid, unsigned int devid)
+{
+ device *device;
+ char token[20];
+ struct path p;
+ char *val;
+
+ device = calloc(1, sizeof(*device));
+ if ( !device )
+ {
+ syslog(LOG_CRIT, "Got no memory for new device %u/%u", domid, devid);
+ return NULL;
+ }
+
+ device->domid = domid;
+ device->devid = devid;
+
+ construct_frontend_path(device, "state", &p);
+ snprintf(token, sizeof(token), "%u/%u", domid, devid);
+ if ( !xs_watch(xs, p.path, token) )
+ {
+ syslog(LOG_ERR, "Setting up watch for device %u/%u failed",
+ domid, devid);
+ free(device);
+ return NULL;
+ }
+
+ val = read_backend_node(device, "security_model");
+ if ( !val || strcmp(val, "none") )
+ {
+ syslog(LOG_ERR, "Security model \"%s\" for device %u/%u invalid.",
+ val, domid, devid);
+ free(val);
+ goto err;
+ }
+ free(val);
+
+ device->max_space = read_backend_node_uint(device, "max-space", 0);
+ device->max_files = read_backend_node_uint(device, "max-files", 0);
+ device->max_open_files =
+ read_backend_node_uint(device, "max-open-files", 0)
+ ?: MAX_OPEN_FILES_DEFAULT;
+ device->auto_delete = read_backend_node_uint(device, "auto-delete", 0);
+
+ device->host_path = read_backend_node(device, "path");
+ if ( check_host_path(device) )
+ {
+ syslog(LOG_ERR, "Host path \"%s\" for device %u/%u invalid.",
+ device->host_path, domid, devid);
+ goto err;
+ }
+
+ if ( write_backend_node(device, "versions", "1") )
+ goto err;
+ if ( write_backend_node_uint(device, "max-rings", MAX_RINGS) )
+ goto err;
+ if ( write_backend_node_uint(device, "max-ring-page-order",
+ MAX_RING_ORDER) )
+ goto err;
+
+ if ( write_backend_state(device, XenbusStateInitWait) )
+ goto err;
+
+ XEN_TAILQ_INSERT_TAIL(&devs, device, list);
+ syslog(LOG_INFO, "New device %u/%u added", domid, devid);
+
+ return device;
+
+ err:
+ free_device(device);
+ return NULL;
+}
+
+static void disconnect_ring(struct ring *ring)
+{
+ if ( !ring )
+ return;
+
+ if ( ring->thread_active )
+ {
+ ring->stop_thread = true;
+ pthread_cond_signal(&ring->cond);
+ pthread_join(ring->thread, NULL);
+ ring->stop_thread = false;
+ }
+
+ if ( ring->data.in )
+ {
+ xengnttab_unmap(xg, ring->data.in, 1 << ring->ring_order);
+ ring->data.in = NULL;
+ }
+ if ( ring->intf )
+ {
+ xengnttab_unmap(xg, ring->intf, 1 );
+ ring->intf = NULL;
+ }
+
+ if ( ring->evtchn )
+ {
+ xenevtchn_unbind(xe, ring->evtchn);
+ ring->evtchn = 0;
+ }
+
+ pthread_mutex_destroy(&ring->mutex);
+ pthread_cond_destroy(&ring->cond);
+}
+
+static void disconnect_guest(device *device)
+{
+ unsigned int ring_idx;
+
+ for ( ring_idx = 0; ring_idx < device->num_rings; ring_idx++ )
+ {
+ disconnect_ring(device->ring[ring_idx]);
+ free(device->ring[ring_idx]);
+ device->ring[ring_idx] = NULL;
+ }
+
+ device->num_rings = 0;
+}
+
+static void close_device(device *device, enum xenbus_state state)
+{
+ disconnect_guest(device);
+ write_backend_state(device, state);
+}
+
+static void connect_err(device *device, const char *msg)
+{
+ syslog(LOG_WARNING, "%s", msg);
+ close_device(device, XenbusStateClosed);
+}
+
+static void connect_device(device *device)
+{
+ unsigned int val;
+ unsigned int ring_idx;
+ char node[20];
+ struct ring *ring;
+ xenevtchn_port_or_error_t evtchn;
+
+ val = read_frontend_node_uint(device, "version", 0);
+ if ( val != 1 )
+ return connect_err(device, "frontend specifies illegal version");
+ device->num_rings = read_frontend_node_uint(device, "num-rings", 0);
+ if ( device->num_rings < 1 || device->num_rings > MAX_RINGS )
+ return connect_err(device, "frontend specifies illegal ring number");
+
+ for ( ring_idx = 0; ring_idx < device->num_rings; ring_idx++ )
+ {
+ ring = calloc(1, sizeof(*ring));
+ if ( !ring )
+ return connect_err(device, "could not allocate ring memory");
+ device->ring[ring_idx] = ring;
+ ring->device = device;
+ pthread_cond_init(&ring->cond, NULL);
+ pthread_mutex_init(&ring->mutex, NULL);
+
+
+ snprintf(node, sizeof(node), "event-channel-%u", ring_idx);
+ val = read_frontend_node_uint(device, node, 0);
+ if ( val == 0 )
+ return connect_err(device, "frontend specifies illegal evtchn");
+ evtchn = xenevtchn_bind_interdomain(xe, device->domid, val);
+ if ( evtchn < 0 )
+ return connect_err(device, "could not bind to event channel");
+ ring->evtchn = evtchn;
+
+ snprintf(node, sizeof(node), "ring-ref%u", ring_idx);
+ val = read_frontend_node_uint(device, node, 0);
+ if ( val == 0 )
+ return connect_err(device,
+ "frontend specifies illegal grant for ring");
+ ring->intf = xengnttab_map_grant_ref(xg, device->domid, val,
+ PROT_READ | PROT_WRITE);
+ if ( !ring->intf )
+ return connect_err(device, "could not map interface page");
+ ring->ring_order = ring->intf->ring_order;
+ if ( ring->ring_order > MAX_RING_ORDER || ring->ring_order < 1 )
+ return connect_err(device, "frontend specifies illegal ring
order");
+ ring->ring_size = XEN_FLEX_RING_SIZE(ring->ring_order);
+ ring->data.in = xengnttab_map_domain_grant_refs(xg,
+ 1 << ring->ring_order,
+ device->domid,
+ ring->intf->ref,
+ PROT_READ |
PROT_WRITE);
+ if ( !ring->data.in )
+ return connect_err(device, "could not map ring pages");
+ ring->data.out = ring->data.in + ring->ring_size;
+
+ if ( pthread_create(&ring->thread, NULL, io_thread, ring) )
+ return connect_err(device, "could not start I/O thread");
+ ring->thread_active = true;
+ }
+
+ write_backend_state(device, XenbusStateConnected);
+}
+
+static void remove_device(device *device)
+{
+ XEN_TAILQ_REMOVE(&devs, device, list);
+
+ disconnect_guest(device);
+ free_device(device);
+}
+
+static void remove_all_devices(void)
+{
+ device *device, *tmp;
+
+ XEN_TAILQ_FOREACH_SAFE( device, &devs, list, tmp )
+ remove_device(device);
+}
+
+static void frontend_changed(device *device)
+{
+ struct path p;
+ char *state, *end;
+ unsigned int len;
+ unsigned long new_state;
+
+ construct_frontend_path(device, "state", &p);
+ state = xs_read(xs, XBT_NULL, p.path, &len);
+ if ( !state )
+ {
+ close_device(device, XenbusStateClosed);
+ return;
+ }
+
+ new_state = strtoul(state, &end, 10);
+ if ( *end || new_state > XenbusStateReconfigured )
+ {
+ syslog(LOG_WARNING, "unknown state \"%s\" seen for device %u/%u",
state,
+ device->domid, device->devid);
+ new_state = XenbusStateUnknown;
+ }
+ free(state);
+
+ if ( new_state == device->frontend_state )
+ return;
+
+ switch ( new_state )
+ {
+ case XenbusStateInitialising:
+ break;
+
+ case XenbusStateInitialised:
+ connect_device(device);
+ break;
+
+ case XenbusStateConnected:
+ break;
+
+ case XenbusStateClosing:
+ close_device(device, XenbusStateClosing);
+ break;
+
+ case XenbusStateClosed:
+ close_device(device, XenbusStateClosed);
+ break;
+
+ default:
+ syslog(LOG_WARNING, "not handled frontend state %lu for device %u/%u",
+ new_state, device->domid, device->devid);
+ break;
+ }
+
+ device->frontend_state = new_state;
+}
+
+static void check_device(unsigned int domid, unsigned int devid)
+{
+ device *device;
+
+ device = find_device(domid, devid);
+ if ( !device )
+ {
+ device = new_device(domid, devid);
+ if ( !device )
+ return;
+ }
+
+ device->last_seen = now;
+}
+
+static void scan_backend(void)
+{
+ char **doms;
+ unsigned int n_doms, dom;
+ char **devices;
+ unsigned int n_devs, dev;
+ char dom_path[24];
+ unsigned long domid, devid;
+ char *end;
+ device *device, *tmp;
+
+ now++;
+
+ doms = xs_directory(xs, XBT_NULL, "backend/xen_9pfs", &n_doms);
+ if ( doms == NULL )
+ return;
+
+ for ( dom = 0; dom < n_doms; dom++ )
+ {
+ errno = 0;
+ domid = strtoul(doms[dom], &end, 10);
+ if ( errno || *end || domid >= DOMID_FIRST_RESERVED )
+ continue;
+
+ snprintf(dom_path, sizeof(dom_path), "backend/xen_9pfs/%lu", domid);
+ devices = xs_directory(xs, XBT_NULL, dom_path, &n_devs);
+
+ for ( dev = 0; dev < n_devs; dev++ )
+ {
+ errno = 0;
+ devid = strtoul(devices[dev], &end, 10);
+ if ( errno || *end || devid > UINT_MAX )
+ continue;
+
+ check_device(domid, devid);
+ }
+
+ free(devices);
+ }
+
+ free(doms);
+
+ XEN_TAILQ_FOREACH_SAFE( device, &devs, list, tmp )
+ {
+ if ( device->last_seen != now )
+ remove_device(device);
+ }
+}
+
+static void handle_watch(char *path, char *token)
+{
+ unsigned int domid, devid;
+ device *device;
+
+ if ( !strcmp(token, "main") )
+ {
+ scan_backend();
+ return;
+ }
+
+ if ( sscanf(token, "%u/%u", &domid, &devid) != 2 )
+ {
+ syslog(LOG_WARNING, "unknown watch event %s %s", path, token);
+ return;
+ }
+
+ device = find_device(domid, devid);
+ if ( !device )
+ {
+ syslog(LOG_WARNING, "watch event for unknown device %u/%u",
+ domid, devid);
+ return;
+ }
+
+ frontend_changed(device);
+}
+
static void close_all(void)
{
if ( daemon_running )
+ {
xs_rm(xs, XBT_NULL, "libxl/xen-9pfs");
+ xs_unwatch(xs, "backend/xen_9pfs", "main");
+
+ remove_all_devices();
+ }
if ( xe )
xenevtchn_close(xe);
if ( xg )
@@ -68,6 +638,33 @@ static void do_err(const char *msg)
exit(1);
}
+static void handle_event(void)
+{
+ xenevtchn_port_or_error_t evtchn;
+ device *device;
+ struct ring *ring;
+ unsigned int ring_idx;
+
+ evtchn = xenevtchn_pending(xe);
+ if ( evtchn < 0 )
+ do_err("xenevtchn_pending() failed");
+
+ XEN_TAILQ_FOREACH( device, &devs, list )
+ {
+ for ( ring_idx = 0; ring_idx < device->num_rings; ring_idx++ )
+ {
+ ring = device->ring[ring_idx];
+ if ( ring && ring->evtchn == evtchn )
+ {
+ pthread_mutex_lock(&ring->mutex);
+ pthread_cond_signal(&ring->cond);
+ pthread_mutex_unlock(&ring->mutex);
+ return;
+ }
+ }
+ }
+}
+
static void xen_connect(void)
{
xs_transaction_t t;
@@ -122,6 +719,11 @@ int main(int argc, char *argv[])
int syslog_mask = LOG_MASK(LOG_WARNING) | LOG_MASK(LOG_ERR) |
LOG_MASK(LOG_CRIT) | LOG_MASK(LOG_ALERT) |
LOG_MASK(LOG_EMERG);
+ char **watch;
+ struct pollfd p[2] = {
+ { .events = POLLIN },
+ { .events = POLLIN }
+ };
umask(027);
if ( getenv("XEN_9PFSD_VERBOSE") )
@@ -134,9 +736,26 @@ int main(int argc, char *argv[])
xen_connect();
+ if ( !xs_watch(xs, "backend/xen_9pfs", "main") )
+ do_err("xs_watch() in main thread failed");
+ p[0].fd = xs_fileno(xs);
+ p[1].fd = xenevtchn_fd(xe);
+
+ scan_backend();
+
while ( !stop_me )
{
- sleep(60);
+ while ( (p[0].revents & POLLIN) &&
+ (watch = xs_check_watch(xs)) != NULL )
+ {
+ handle_watch(watch[XS_WATCH_PATH], watch[XS_WATCH_TOKEN]);
+ free(watch);
+ }
+
+ if ( p[1].revents & POLLIN )
+ handle_event();
+
+ poll(p, 2, -1);
}
close_all();
diff --git a/tools/xen-9pfsd/xen-9pfsd.h b/tools/xen-9pfsd/xen-9pfsd.h
new file mode 100644
index 0000000000..432f321d0d
--- /dev/null
+++ b/tools/xen-9pfsd/xen-9pfsd.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef XEN_9PFSD_H
+#define XEN_9PFSD_H
+
+#include <pthread.h>
+#include <stdbool.h>
+#include <xenevtchn.h>
+#include <xen_list.h>
+#include <xen/xen.h>
+#include <xen/io/xenbus.h>
+#include <xen/io/9pfs.h>
+
+#define MAX_RINGS 4
+#define MAX_RING_ORDER 9
+#define MAX_OPEN_FILES_DEFAULT 5
+
+typedef struct device device;
+
+struct ring {
+ device *device;
+ pthread_t thread;
+ bool thread_active;
+ bool stop_thread;
+ pthread_cond_t cond;
+ pthread_mutex_t mutex;
+
+ evtchn_port_t evtchn;
+ struct xen_9pfs_data_intf *intf;
+ unsigned int ring_order;
+ RING_IDX ring_size;
+ struct xen_9pfs_data data;
+};
+
+struct device {
+ /* Admin data. */
+ XEN_TAILQ_ENTRY(device) list;
+ unsigned int last_seen; /* Set in scan_backend(). */
+ unsigned int domid;
+ unsigned int devid;
+
+ /* Tool side configuration data. */
+ char *host_path;
+ unsigned int max_space;
+ unsigned int max_files;
+ unsigned int max_open_files;
+ bool auto_delete;
+
+ /* Connection data. */
+ enum xenbus_state backend_state;
+ enum xenbus_state frontend_state;
+ unsigned int num_rings;
+ struct ring *ring[MAX_RINGS];
+};
+
+extern xenevtchn_handle *xe;
+
+void *io_thread(void *arg);
+
+#endif /* XEN_9PFSD_H */
--
2.35.3
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