sched/gettid: Move thread ID to TLS

There is no need for a gettid() syscall, as the thread ID is stable through
the life of the process. It is safe to put a copy of TID to TLS. This way
a user processes can access TID quickly via its own stack, instead of
having to use an expensive syscall.

Signed-off-by: Ville Juven <ville.juven@unikie.com>

include/nuttx/tls.h

@@ -223,6 +223,7 @@ struct tls_info_s
 
   uint16_t tl_size;                    /* Actual size with alignments */
   int tl_errno;                        /* Per-thread error number */
+  pid_t tl_tid;                        /* Thread ID */
 };
 
 /****************************************************************************

include/sys/syscall_lookup.h

@@ -29,7 +29,6 @@
 SYSCALL_LOOKUP1(_exit,                     1)
 SYSCALL_LOOKUP(_assert,                    4)
 SYSCALL_LOOKUP(getpid,                     0)
-SYSCALL_LOOKUP(gettid,                     0)
 SYSCALL_LOOKUP(prctl,                      2)
 
 #ifdef CONFIG_SCHED_HAVE_PARENT

libs/libc/sched/CMakeLists.txt

@@ -28,7 +28,8 @@ set(SRCS
     task_cancelpt.c
     task_setcancelstate.c
     task_setcanceltype.c
-    task_testcancel.c)
+    task_testcancel.c
+    task_gettid.c)
 
 if(CONFIG_SMP)
   list(APPEND SRCS sched_cpucount.c)

libs/libc/sched/Make.defs

@@ -25,7 +25,7 @@
 CSRCS += sched_getprioritymax.c sched_getprioritymin.c
 CSRCS += clock_getcpuclockid.c clock_getres.c
 CSRCS += task_cancelpt.c task_setcancelstate.c task_setcanceltype.c
-CSRCS += task_testcancel.c
+CSRCS += task_testcancel.c task_gettid.c
 
 ifeq ($(CONFIG_SMP),y)
 CSRCS += sched_cpucount.c

libs/libc/sched/task_gettid.c

@@ -0,0 +1,56 @@
+/****************************************************************************
+ * libs/libc/sched/task_gettid.c
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <nuttx/tls.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: gettid
+ *
+ * Description:
+ *   Get the thread ID of the currently executing thread.
+ *
+ * Input parameters:
+ *   None
+ *
+ * Returned Value:
+ *   On success, returns the thread ID of the calling process.
+ *
+ ****************************************************************************/
+
+pid_t gettid(void)
+{
+  FAR struct tls_info_s *tls = tls_get_info();
+  return tls->tl_tid;
+}

sched/pthread/pthread_create.c

@@ -281,15 +281,6 @@ int nx_pthread_create(pthread_trampoline_t trampoline, FAR pthread_t *thread,
     }
 #endif
 
-  /* Initialize thread local storage */
-
-  ret = tls_init_info(&ptcb->cmn);
-  if (ret != OK)
-    {
-      errcode = -ret;
-      goto errout_with_tcb;
-    }
-
   /* Should we use the priority and scheduler specified in the pthread
    * attributes?  Or should we use the current thread's priority and
    * scheduler?
@@ -397,6 +388,15 @@ int nx_pthread_create(pthread_trampoline_t trampoline, FAR pthread_t *thread,
       goto errout_with_tcb;
     }
 
+  /* Initialize thread local storage */
+
+  ret = tls_init_info(&ptcb->cmn);
+  if (ret != OK)
+    {
+      errcode = -ret;
+      goto errout_with_tcb;
+    }
+
 #ifdef CONFIG_SMP
   /* pthread_setup_scheduler() will set the affinity mask by inheriting the
    * setting from the parent task.  We need to override this setting

sched/task/task_gettid.c

@@ -91,22 +91,3 @@ pid_t nxsched_gettid(void)
 
   return 0;
 }
-
-/****************************************************************************
- * Name: gettid
- *
- * Description:
- *   Get the thread ID of the currently executing thread.
- *
- * Input parameters:
- *   None
- *
- * Returned Value:
- *   On success, returns the thread ID of the calling process.
- *
- ****************************************************************************/
-
-pid_t gettid(void)
-{
-  return nxsched_gettid();
-}

sched/task/task_init.c

@@ -168,18 +168,18 @@ int nxtask_init(FAR struct task_tcb_s *tcb, const char *name, int priority,
       goto errout_with_group;
     }
 
-  /* Initialize thread local storage */
+  /* Initialize the task control block */
 
-  ret = tls_init_info(&tcb->cmn);
+  ret = nxtask_setup_scheduler(tcb, priority, nxtask_start,
+                               entry, ttype);
   if (ret < OK)
     {
       goto errout_with_group;
     }
 
-  /* Initialize the task control block */
+  /* Initialize thread local storage */
 
-  ret = nxtask_setup_scheduler(tcb, priority, nxtask_start,
-                               entry, ttype);
+  ret = tls_init_info(&tcb->cmn);
   if (ret < OK)
     {
       goto errout_with_group;

sched/tls/tls_initinfo.c

@@ -73,5 +73,10 @@ int tls_init_info(FAR struct tcb_s *tcb)
   /* Attach per-task info in group to TLS */
 
   info->tl_task = tcb->group->tg_info;
+
+  /* Thread ID */
+
+  info->tl_tid = tcb->pid;
+
   return OK;
 }

syscall/syscall.csv

@@ -48,7 +48,6 @@
 "getppid","unistd.h","defined(CONFIG_SCHED_HAVE_PARENT)","pid_t"
 "getsockname","sys/socket.h","defined(CONFIG_NET)","int","int","FAR struct sockaddr *","FAR socklen_t *"
 "getsockopt","sys/socket.h","defined(CONFIG_NET)","int","int","int","int","FAR void *","FAR socklen_t *"
-"gettid","unistd.h","","pid_t"
 "gettimeofday","sys/time.h","","int","FAR struct timeval *","FAR struct timezone *"
 "getuid","unistd.h","defined(CONFIG_SCHED_USER_IDENTITY)","uid_t"
 "inotify_add_watch","sys/inotify.h","defined(CONFIG_FS_NOTIFY)","int","int","FAR const char *","uint32_t"