diff options
Diffstat (limited to 'apps/nshlib/nsh_builtin.c')
| -rw-r--r-- | apps/nshlib/nsh_builtin.c | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/apps/nshlib/nsh_builtin.c b/apps/nshlib/nsh_builtin.c index 343a0824b..0d5a0231c 100644 --- a/apps/nshlib/nsh_builtin.c +++ b/apps/nshlib/nsh_builtin.c @@ -131,12 +131,14 @@ int nsh_builtin(FAR struct nsh_vtbl_s *vtbl, FAR const char *cmd, { /* The application was successfully started with pre-emption disabled. * In the simplest cases, the application will not have run because the - * the scheduler is locked. but in the case were I/O redirected, a - * proxy task ran and, as result, so may have the application. + * the scheduler is locked. But in the case where I/O was redirected, a + * proxy task ran and broke our lock. As result, the application may + * have aso ran if its priority was higher than than the priority of + * this thread. * - * If the application did not run and if the application was not - * backgrounded, then we need to wait here for the application to - * exit. This only works works with the following options: + * If the application did not run to completion and if the application + * was not backgrounded, then we need to wait here for the application + * to exit. This only works works with the following options: * * - CONFIG_NSH_DISABLEBG - Do not run commands in background * - CONFIG_SCHED_WAITPID - Required to run external commands in @@ -156,11 +158,17 @@ int nsh_builtin(FAR struct nsh_vtbl_s *vtbl, FAR const char *cmd, { int rc = 0; - /* Wait for the application to exit. We did locked the scheduler + /* Wait for the application to exit. We did lock the scheduler * above, but that does not guarantee that the application did not - * run in the case where I/O was redirected. The scheduler will - * be unlocked while waitpid is waiting and if the application has - * not yet run, it will be able to to do so. + * already run to completion in the case where I/O was redirected. + * Here the scheduler will be unlocked while waitpid is waiting + * and if the application has not yet run, it will now be able to + * do so. + * + * Also, if CONFIG_SCHED_HAVE_PARENT is defined waitpid() might fail + * even if task is still active: If the I/O was re-directed by a + * proxy task, then the ask is a child of the proxy, and not this + * task. waitpid() fails with ECHILD in either case. */ ret = waitpid(ret, &rc, 0); |