[kernel] Add a timeout to endpoint recieve syscalls

This also required adding support for multiple wait conditions on a
thread, so wait_type is an enum_bitfield now.

I really need a real clock.

src/kernel/objects/endpoint.cpp

@@ -2,6 +2,7 @@
 #include "objects/endpoint.h"
 #include "objects/process.h"
 #include "objects/thread.h"
+#include "scheduler.h"
 #include "vm_space.h"
 
 endpoint::endpoint() :
@@ -55,16 +56,20 @@ endpoint::send(j6_tag_t tag, const void *data, size_t data_len)
 }
 
 j6_status_t
-endpoint::receive(j6_tag_t *tag, void *data, size_t *data_len)
+endpoint::receive(j6_tag_t *tag, void *data, size_t *data_len, uint64_t timeout)
 {
     thread_data receiver = { &thread::current(), data };
     receiver.tag_p = tag;
     receiver.len_p = data_len;
 
+    // Timeout is a duration, but wait_on_* calls need a time
+    if (timeout)
+        timeout += scheduler::get().clock();
+
     if (!check_signal(j6_signal_endpoint_can_recv)) {
         assert_signal(j6_signal_endpoint_can_send);
         m_blocked.append(receiver);
-        receiver.th->wait_on_object(this);
+        receiver.th->wait_on_object(this, timeout);
 
         // we woke up having already finished the recv
         // because it happened in the sender

src/kernel/objects/endpoint.h

@@ -36,11 +36,12 @@ public:
 
     /// Receive a message from a thread waiting to send on this endpoint. If no threads
     /// are currently trying to send, block the current thread.
-    /// \arg tag   [in] The sender-specified message tag
-    /// \arg len   [in] The size in bytes of the buffer [out] Number of bytes in the message
-    /// \arg data  Buffer for copying message data into
-    /// \returns   j6_status_ok on success
-    j6_status_t receive(j6_tag_t *tag, void *data, size_t *data_len);
+    /// \arg tag     [in] The sender-specified message tag
+    /// \arg len     [in] The size in bytes of the buffer [out] Number of bytes in the message
+    /// \arg data    Buffer for copying message data into
+    /// \arg timeout Receive timeout in nanoseconds
+    /// \returns     j6_status_ok on success
+    j6_status_t receive(j6_tag_t *tag, void *data, size_t *data_len, uint64_t timeout = 0);
 
     /// Give the listener on the endpoint a message that a bound IRQ has been signalled
     /// \arg irq  The IRQ that caused this signal

src/kernel/objects/thread.cpp

@@ -47,37 +47,52 @@ inline void schedule_if_current(thread *t) { if (t == current_cpu().thread) sche
 void
 thread::wait_on_signals(j6_signal_t signals)
 {
-    m_wait_type = wait_type::signal;
-    m_wait_data = signals;
-    clear_state(state::ready);
-
+    {
+        util::scoped_lock {m_wait_lock};
+        m_wait_type = wait_type::signal;
+        m_wait_data = signals;
+        clear_state(state::ready);
+    }
     schedule_if_current(this);
 }
 
 void
 thread::wait_on_time(uint64_t t)
 {
-    m_wait_type = wait_type::time;
-    m_wait_data = t;
-    clear_state(state::ready);
-
+    {
+        util::scoped_lock {m_wait_lock};
+        m_wait_type = wait_type::time;
+        m_wait_time = t;
+        clear_state(state::ready);
+    }
     schedule_if_current(this);
 }
 
 void
-thread::wait_on_object(kobject *o)
+thread::wait_on_object(kobject *o, uint64_t t)
 {
-    m_wait_type = wait_type::object;
-    m_wait_data = reinterpret_cast<uint64_t>(o);
-    clear_state(state::ready);
+    {
+        util::scoped_lock {m_wait_lock};
 
+        m_wait_type = wait_type::object;
+        m_wait_data = reinterpret_cast<uint64_t>(o);
+
+        if (t) {
+            m_wait_type |= wait_type::time;
+            m_wait_time = t;
+        }
+
+        clear_state(state::ready);
+    }
     schedule_if_current(this);
 }
 
 bool
 thread::wake_on_signals(kobject *obj, j6_signal_t signals)
 {
-    if (m_wait_type != wait_type::signal ||
+    util::scoped_lock {m_wait_lock};
+
+    if (!(m_wait_type & wait_type::signal) ||
         (signals & m_wait_data) == 0)
         return false;
 
@@ -92,12 +107,18 @@ thread::wake_on_signals(kobject *obj, j6_signal_t signals)
 bool
 thread::wake_on_time(uint64_t now)
 {
-    if (m_wait_type != wait_type::time ||
-        now < m_wait_data)
+    util::scoped_lock {m_wait_lock};
+
+    if (!(m_wait_type & wait_type::time) ||
+        now < m_wait_time)
         return false;
 
+    if (!(m_wait_type & ~wait_type::none))
+        m_wait_result = j6_status_ok;
+    else
+        m_wait_result = j6_err_timed_out;
+
     m_wait_type = wait_type::none;
-    m_wait_result = j6_status_ok;
     m_wait_data = now;
     m_wait_obj = 0;
     set_state(state::ready);
@@ -107,7 +128,9 @@ thread::wake_on_time(uint64_t now)
 bool
 thread::wake_on_object(kobject *o)
 {
-    if (m_wait_type != wait_type::object ||
+    util::scoped_lock {m_wait_lock};
+
+    if (!(m_wait_type & wait_type::object) ||
         reinterpret_cast<uint64_t>(o) != m_wait_data)
         return false;
 
@@ -121,6 +144,8 @@ thread::wake_on_object(kobject *o)
 void
 thread::wake_on_result(kobject *obj, j6_status_t result)
 {
+    util::scoped_lock {m_wait_lock};
+
     m_wait_type = wait_type::none;
     m_wait_result = result;
     m_wait_data = 0;

src/kernel/objects/thread.h

@@ -2,7 +2,9 @@
 /// \file thread.h
 /// Definition of thread kobject types
 
+#include <util/enum_bitfields.h>
 #include <util/linked_list.h>
+#include <util/spinlock.h>
 
 #include "objects/kobject.h"
 
@@ -36,11 +38,20 @@ struct TCB
 using tcb_list = util::linked_list<TCB>;
 using tcb_node = tcb_list::item_type;
 
+enum class wait_type : uint8_t
+{
+    none   = 0x00,
+    signal = 0x01,
+    time   = 0x02,
+    object = 0x04,
+};
+is_bitfield(wait_type);
+
 class thread :
     public kobject
 {
 public:
-    enum class wait_type : uint8_t { none, signal, time, object };
+
     enum class state : uint8_t {
         ready    = 0x01,
         loading  = 0x02,
@@ -85,8 +96,9 @@ public:
     void wait_on_time(uint64_t t);
 
     /// Block the thread, waiting on the given object
-    /// \arg o  The ojbect that should wake this thread
-    void wait_on_object(kobject *o);
+    /// \arg o  The object that should wake this thread
+    /// \arg t  The timeout clock value to wait for
+    void wait_on_object(kobject *o, uint64_t t = 0);
 
     /// Wake the thread if it is waiting on signals.
     /// \arg obj     Object that changed signals
@@ -184,8 +196,10 @@ private:
     int32_t m_return_code;
 
     uint64_t m_wait_data;
+    uint64_t m_wait_time;
     j6_status_t m_wait_result;
     j6_koid_t m_wait_obj;
+    util::spinlock m_wait_lock;
 
     j6_handle_t m_self_handle;
 };

src/kernel/scheduler.h

@@ -72,6 +72,8 @@ public:
     /// \arg t  The new thread's TCB
     void add_thread(TCB *t);
 
+    uint64_t clock() const { return m_clock; }
+
     /// Get a reference to the scheduler
     /// \returns  A reference to the global system scheduler
     static scheduler & get() { return *s_instance; }

src/kernel/syscalls/endpoint.cpp

@@ -27,7 +27,7 @@ endpoint_send(j6_handle_t handle, uint64_t tag, const void * data, size_t data_l
 }
 
 j6_status_t
-endpoint_receive(j6_handle_t handle, uint64_t * tag, void * data, size_t * data_len)
+endpoint_receive(j6_handle_t handle, uint64_t * tag, void * data, size_t * data_len, uint64_t timeout)
 {
     if (!tag || !data_len || (*data_len && !data))
         return j6_err_invalid_arg;
@@ -37,14 +37,14 @@ endpoint_receive(j6_handle_t handle, uint64_t * tag, void * data, size_t * data_
 
     j6_tag_t out_tag = j6_tag_invalid;
     size_t out_len = *data_len;
-    j6_status_t s = e->receive(&out_tag, data, &out_len);
+    j6_status_t s = e->receive(&out_tag, data, &out_len, timeout);
     *tag = out_tag;
     *data_len = out_len;
     return s;
 }
 
 j6_status_t
-endpoint_sendrecv(j6_handle_t handle, uint64_t * tag, void * data, size_t * data_len)
+endpoint_sendrecv(j6_handle_t handle, uint64_t * tag, void * data, size_t * data_len, uint64_t timeout)
 {
     if (!tag || (*tag & j6_tag_system_flag))
         return j6_err_invalid_arg;
@@ -58,7 +58,7 @@ endpoint_sendrecv(j6_handle_t handle, uint64_t * tag, void * data, size_t * data
 
     j6_tag_t out_tag = j6_tag_invalid;
     size_t out_len = *data_len;
-    j6_status_t s = e->receive(&out_tag, data, &out_len);
+    j6_status_t s = e->receive(&out_tag, data, &out_len, timeout);
     *tag = out_tag;
     *data_len = out_len;
     return s;

src/libraries/j6/include/j6/errors.h

@@ -17,4 +17,5 @@
 #define j6_err_invalid_arg          j6_err(0x0003)
 #define j6_err_not_ready            j6_err(0x0004)
 #define j6_err_insufficient         j6_err(0x0005)
+#define j6_err_timed_out            j6_err(0x0006)