sergiotarxz/nuttx-apps
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Lock the scheduler when starting NSH builtin applications to eliminate race conditions

Browse Source 
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4988 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo 2012-07-28 18:38:13 +00:00
parent cea531d7dc
commit 52fe89eb98
3 changed files with 75 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
ChangeLog.txt
View File

@ -260,4 +260,6 @@
termios ioctls, then don't bother trying to configure the baud, parity
etc.
* apps/nslib: If waitpid() is supported, then NSH not catches the
return value from spawned applications.
return value from spawned applications (provided by Mike Smith)
* apps/nslib: Lock the schedule while starting built-in applications
in order to eliminate race conditions (also from Mike Smith).

45
nshlib/nsh_apps.c
View File

@ -90,7 +90,9 @@
* Attempt to execute the application task whose name is 'cmd'
*
* Returned Value:
* -1 (ERRROR) if the application task corresponding to 'cmd' could not
* <0 If exec_namedapp() fails, then the negated errno value
* is returned.
* -1 (ERROR) if the application task corresponding to 'cmd' could not
* be started (possibly because it doesn not exist).
* 0 (OK) if the application task corresponding to 'cmd' was
* and successfully started. If CONFIG_SCHED_WAITPID is
@ -107,21 +109,39 @@ int nsh_execapp(FAR struct nsh_vtbl_s *vtbl, FAR const char *cmd,
{
int ret = OK;
/* Try to find command within pre-built application list. */
/* Lock the scheduler to prevent the application from running until the
* waitpid() has been called.
*/
sched_lock();
/* Try to find and execute the command within the list of builtin
* applications.
*/
ret = exec_namedapp(cmd, (FAR const char **)argv);
if (ret < 0)
if (ret >= 0)
{
return -errno;
}
/* The application was successfully started (but still blocked because the
* scheduler is locked). If the application was not backgrounded, then we
* need to wait here for the application to exit.
*/
#ifdef CONFIG_SCHED_WAITPID
if (vtbl->np.np_bg == false)
{
int rc = 0;
waitpid(ret, &rc, 0);
/* Wait for the application to exit. Since we have locked the
* scheduler above, we know that the application has not yet
* started and there is no possibility that it has already exited.
* The scheduler will be unlocked while waitpid is waiting and the
* application will be able to run.
*/
ret = waitpid(ret, &rc, 0);
if (ret >= 0)
{
/* We can't return the exact status (nsh has nowhere to put it)
* so just pass back zero/nonzero in a fashion that doesn't look
* like an error.
@ -134,6 +154,7 @@ int nsh_execapp(FAR struct nsh_vtbl_s *vtbl, FAR const char *cmd,
* the most recently executed task.
*/
}
}
else
#endif
{
@ -147,6 +168,18 @@ int nsh_execapp(FAR struct nsh_vtbl_s *vtbl, FAR const char *cmd,
ret = OK;
}
}
sched_unlock();
/* If exec_namedapp() or waitpid() failed, then return the negated errno
* value.
*/
if (ret < 0)
{
return -errno;
}
return ret;
}

6
nshlib/nsh_parse.c
View File

@ -492,6 +492,8 @@ static int cmd_exit(FAR struct nsh_vtbl_s *vtbl, int argc, char **argv)
* Exectue the command in argv[0]
*
* Returned Value:
* <0 If exec_namedapp() fails, then the negated errno value
* is returned.
* -1 (ERRROR) if the command was unsuccessful
* 0 (OK) if the command was successful
* 1 if an application task was spawned successfully, but
@ -521,8 +523,8 @@ static int nsh_execute(FAR struct nsh_vtbl_s *vtbl, int argc, char *argv[])
#ifdef CONFIG_NSH_BUILTIN_APPS
ret = nsh_execapp(vtbl, cmd, argv);
/* The pre-built application was successfully started -- return OK
* or 1 if it returned a non-zero exit status.
/* If the built-in application was successfully started, return OK
* or 1 (if the application returned a non-zero exit status).
*/
if (ret >= 0)