diff options
Diffstat (limited to 'drivers/xen/xenbus/xenbus_xs.c')
| -rw-r--r-- | drivers/xen/xenbus/xenbus_xs.c | 194 |
1 files changed, 157 insertions, 37 deletions
diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c index 7f2f91c0e11..ba804f3d827 100644 --- a/drivers/xen/xenbus/xenbus_xs.c +++ b/drivers/xen/xenbus/xenbus_xs.c @@ -31,6 +31,8 @@ * IN THE SOFTWARE. */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + #include <linux/unistd.h> #include <linux/errno.h> #include <linux/types.h> @@ -44,8 +46,11 @@ #include <linux/rwsem.h> #include <linux/module.h> #include <linux/mutex.h> +#include <asm/xen/hypervisor.h> #include <xen/xenbus.h> +#include <xen/xen.h> #include "xenbus_comms.h" +#include "xenbus_probe.h" struct xs_stored_msg { struct list_head list; @@ -76,6 +81,14 @@ struct xs_handle { /* * Mutex ordering: transaction_mutex -> watch_mutex -> request_mutex. * response_mutex is never taken simultaneously with the other three. + * + * transaction_mutex must be held before incrementing + * transaction_count. The mutex is held when a suspend is in + * progress to prevent new transactions starting. + * + * When decrementing transaction_count to zero the wait queue + * should be woken up, the suspend code waits for count to + * reach zero. */ /* One request at a time. */ @@ -85,7 +98,9 @@ struct xs_handle { struct mutex response_mutex; /* Protect transactions against save/restore. */ - struct rw_semaphore transaction_mutex; + struct mutex transaction_mutex; + atomic_t transaction_count; + wait_queue_head_t transaction_wq; /* Protect watch (de)register against save/restore. */ struct rw_semaphore watch_mutex; @@ -117,15 +132,37 @@ static int get_error(const char *errorstring) for (i = 0; strcmp(errorstring, xsd_errors[i].errstring) != 0; i++) { if (i == ARRAY_SIZE(xsd_errors) - 1) { - printk(KERN_WARNING - "XENBUS xen store gave: unknown error %s", - errorstring); + pr_warn("xen store gave: unknown error %s\n", + errorstring); return EINVAL; } } return xsd_errors[i].errnum; } +static bool xenbus_ok(void) +{ + switch (xen_store_domain_type) { + case XS_LOCAL: + switch (system_state) { + case SYSTEM_POWER_OFF: + case SYSTEM_RESTART: + case SYSTEM_HALT: + return false; + default: + break; + } + return true; + case XS_PV: + case XS_HVM: + /* FIXME: Could check that the remote domain is alive, + * but it is normally initial domain. */ + return true; + default: + break; + } + return false; +} static void *read_reply(enum xsd_sockmsg_type *type, unsigned int *len) { struct xs_stored_msg *msg; @@ -135,9 +172,20 @@ static void *read_reply(enum xsd_sockmsg_type *type, unsigned int *len) while (list_empty(&xs_state.reply_list)) { spin_unlock(&xs_state.reply_lock); - /* XXX FIXME: Avoid synchronous wait for response here. */ - wait_event(xs_state.reply_waitq, - !list_empty(&xs_state.reply_list)); + if (xenbus_ok()) + /* XXX FIXME: Avoid synchronous wait for response here. */ + wait_event_timeout(xs_state.reply_waitq, + !list_empty(&xs_state.reply_list), + msecs_to_jiffies(500)); + else { + /* + * If we are in the process of being shut-down there is + * no point of trying to contact XenBus - it is either + * killed (xenstored application) or the other domain + * has been killed or is unreachable. + */ + return ERR_PTR(-EIO); + } spin_lock(&xs_state.reply_lock); } @@ -157,6 +205,31 @@ static void *read_reply(enum xsd_sockmsg_type *type, unsigned int *len) return body; } +static void transaction_start(void) +{ + mutex_lock(&xs_state.transaction_mutex); + atomic_inc(&xs_state.transaction_count); + mutex_unlock(&xs_state.transaction_mutex); +} + +static void transaction_end(void) +{ + if (atomic_dec_and_test(&xs_state.transaction_count)) + wake_up(&xs_state.transaction_wq); +} + +static void transaction_suspend(void) +{ + mutex_lock(&xs_state.transaction_mutex); + wait_event(xs_state.transaction_wq, + atomic_read(&xs_state.transaction_count) == 0); +} + +static void transaction_resume(void) +{ + mutex_unlock(&xs_state.transaction_mutex); +} + void *xenbus_dev_request_and_reply(struct xsd_sockmsg *msg) { void *ret; @@ -164,7 +237,7 @@ void *xenbus_dev_request_and_reply(struct xsd_sockmsg *msg) int err; if (req_msg.type == XS_TRANSACTION_START) - down_read(&xs_state.transaction_mutex); + transaction_start(); mutex_lock(&xs_state.request_mutex); @@ -177,13 +250,17 @@ void *xenbus_dev_request_and_reply(struct xsd_sockmsg *msg) mutex_unlock(&xs_state.request_mutex); + if (IS_ERR(ret)) + return ret; + if ((msg->type == XS_TRANSACTION_END) || ((req_msg.type == XS_TRANSACTION_START) && (msg->type == XS_ERROR))) - up_read(&xs_state.transaction_mutex); + transaction_end(); return ret; } +EXPORT_SYMBOL(xenbus_dev_request_and_reply); /* Send message to xs, get kmalloc'ed reply. ERR_PTR() on error. */ static void *xs_talkv(struct xenbus_transaction t, @@ -234,10 +311,8 @@ static void *xs_talkv(struct xenbus_transaction t, } if (msg.type != type) { - if (printk_ratelimit()) - printk(KERN_WARNING - "XENBUS unexpected type [%d], expected [%d]\n", - msg.type, type); + pr_warn_ratelimited("unexpected type [%d], expected [%d]\n", + msg.type, type); kfree(ret); return ERR_PTR(-EINVAL); } @@ -431,11 +506,11 @@ int xenbus_transaction_start(struct xenbus_transaction *t) { char *id_str; - down_read(&xs_state.transaction_mutex); + transaction_start(); id_str = xs_single(XBT_NIL, XS_TRANSACTION_START, "", NULL); if (IS_ERR(id_str)) { - up_read(&xs_state.transaction_mutex); + transaction_end(); return PTR_ERR(id_str); } @@ -460,7 +535,7 @@ int xenbus_transaction_end(struct xenbus_transaction t, int abort) err = xs_error(xs_single(t, XS_TRANSACTION_END, abortstr, NULL)); - up_read(&xs_state.transaction_mutex); + transaction_end(); return err; } @@ -495,21 +570,18 @@ int xenbus_printf(struct xenbus_transaction t, { va_list ap; int ret; -#define PRINTF_BUFFER_SIZE 4096 - char *printf_buffer; - - printf_buffer = kmalloc(PRINTF_BUFFER_SIZE, GFP_KERNEL); - if (printf_buffer == NULL) - return -ENOMEM; + char *buf; va_start(ap, fmt); - ret = vsnprintf(printf_buffer, PRINTF_BUFFER_SIZE, fmt, ap); + buf = kvasprintf(GFP_NOIO | __GFP_HIGH, fmt, ap); va_end(ap); - BUG_ON(ret > PRINTF_BUFFER_SIZE-1); - ret = xenbus_write(t, dir, node, printf_buffer); + if (!buf) + return -ENOMEM; + + ret = xenbus_write(t, dir, node, buf); - kfree(printf_buffer); + kfree(buf); return ret; } @@ -583,6 +655,45 @@ static struct xenbus_watch *find_watch(const char *token) return NULL; } +/* + * Certain older XenBus toolstack cannot handle reading values that are + * not populated. Some Xen 3.4 installation are incapable of doing this + * so if we are running on anything older than 4 do not attempt to read + * control/platform-feature-xs_reset_watches. + */ +static bool xen_strict_xenbus_quirk(void) +{ +#ifdef CONFIG_X86 + uint32_t eax, ebx, ecx, edx, base; + + base = xen_cpuid_base(); + cpuid(base + 1, &eax, &ebx, &ecx, &edx); + + if ((eax >> 16) < 4) + return true; +#endif + return false; + +} +static void xs_reset_watches(void) +{ + int err, supported = 0; + + if (!xen_hvm_domain() || xen_initial_domain()) + return; + + if (xen_strict_xenbus_quirk()) + return; + + err = xenbus_scanf(XBT_NIL, "control", + "platform-feature-xs_reset_watches", "%d", &supported); + if (err != 1 || !supported) + return; + + err = xs_error(xs_single(XBT_NIL, XS_RESET_WATCHES, "", NULL)); + if (err && err != -EEXIST) + pr_warn("xs_reset_watches failed: %d\n", err); +} /* Register callback to watch this node. */ int register_xenbus_watch(struct xenbus_watch *watch) @@ -602,8 +713,7 @@ int register_xenbus_watch(struct xenbus_watch *watch) err = xs_watch(watch->node, token); - /* Ignore errors due to multiple registration. */ - if ((err != 0) && (err != -EEXIST)) { + if (err) { spin_lock(&watches_lock); list_del(&watch->list); spin_unlock(&watches_lock); @@ -632,9 +742,7 @@ void unregister_xenbus_watch(struct xenbus_watch *watch) err = xs_unwatch(watch->node, token); if (err) - printk(KERN_WARNING - "XENBUS Failed to release watch %s: %i\n", - watch->node, err); + pr_warn("Failed to release watch %s: %i\n", watch->node, err); up_read(&xs_state.watch_mutex); @@ -661,7 +769,7 @@ EXPORT_SYMBOL_GPL(unregister_xenbus_watch); void xs_suspend(void) { - down_write(&xs_state.transaction_mutex); + transaction_suspend(); down_write(&xs_state.watch_mutex); mutex_lock(&xs_state.request_mutex); mutex_lock(&xs_state.response_mutex); @@ -672,9 +780,11 @@ void xs_resume(void) struct xenbus_watch *watch; char token[sizeof(watch) * 2 + 1]; + xb_init_comms(); + mutex_unlock(&xs_state.response_mutex); mutex_unlock(&xs_state.request_mutex); - up_write(&xs_state.transaction_mutex); + transaction_resume(); /* No need for watches_lock: the watch_mutex is sufficient. */ list_for_each_entry(watch, &watches, list) { @@ -690,7 +800,7 @@ void xs_suspend_cancel(void) mutex_unlock(&xs_state.response_mutex); mutex_unlock(&xs_state.request_mutex); up_write(&xs_state.watch_mutex); - up_write(&xs_state.transaction_mutex); + mutex_unlock(&xs_state.transaction_mutex); } static int xenwatch_thread(void *unused) @@ -763,6 +873,12 @@ static int process_msg(void) goto out; } + if (msg->hdr.len > XENSTORE_PAYLOAD_MAX) { + kfree(msg); + err = -EINVAL; + goto out; + } + body = kmalloc(msg->hdr.len + 1, GFP_NOIO | __GFP_HIGH); if (body == NULL) { kfree(msg); @@ -820,8 +936,7 @@ static int xenbus_thread(void *unused) for (;;) { err = process_msg(); if (err) - printk(KERN_WARNING "XENBUS error %d while reading " - "message\n", err); + pr_warn("error %d while reading message\n", err); if (kthread_should_stop()) break; } @@ -840,8 +955,10 @@ int xs_init(void) mutex_init(&xs_state.request_mutex); mutex_init(&xs_state.response_mutex); - init_rwsem(&xs_state.transaction_mutex); + mutex_init(&xs_state.transaction_mutex); init_rwsem(&xs_state.watch_mutex); + atomic_set(&xs_state.transaction_count, 0); + init_waitqueue_head(&xs_state.transaction_wq); /* Initialize the shared memory rings to talk to xenstored */ err = xb_init_comms(); @@ -857,5 +974,8 @@ int xs_init(void) if (IS_ERR(task)) return PTR_ERR(task); + /* shutdown watches for kexec boot */ + xs_reset_watches(); + return 0; } |