e054f9fb4
Denys Vlasenko
2026-10-05
Subject
ash: waiting machinery: add comments explaining the code
Binary
No binary (build failed)
Architecture & Compiler Flags
—
Build Log
(log yok)
Commit Diff GitHub →
shell/ash.c+20 -3
| @@ -4392,7 +4392,7 @@ static int waitone(int block, struct job *job) | |
| block = (block & ~DOWAIT_JOBSTATUS); | |
| #endif | |
| - | TRACE(("dowait(0x%x) called\n", block)); |
| + | TRACE(("waitone(0x%x) called\n", block)); |
| /* It's wrong to call waitpid() outside of INTOFF region: | |
| * signal can arrive just after syscall return and handler can | |
| @@ -4414,7 +4414,7 @@ static int waitone(int block, struct job *job) | |
| */ | |
| INTOFF; | |
| pid = waitproc(block, &status); | |
| - | TRACE(("wait returns pid %d, status=%d\n", pid, status)); |
| + | TRACE(("waitproc returns pid %d, status=%d\n", pid, status)); |
| if (pid <= 0) | |
| goto out; | |
| @@ -4504,14 +4504,31 @@ static int dowait(int block, struct job *jp) | |
| rpid = 1; | |
| + | /* In what cases we loop here: |
| + | * = If we waited in blocking mode and got pid > 0, |
| + | * but the job we waiting for is still running |
| + | * (jp->state == JOBRUNNING), we have to wait in blocking mode again, |
| + | * until it's not JOBRUNNING. |
| + | * The user is waitforjob(jp) -> dowait(DOWAIT_BLOCK, jp). |
| + | * = If we waited in non-blocking mode and got pid > 0, |
| + | * we should see whether more processes have terminated, |
| + | * we have to wait in non-blocking mode again. |
| + | * The users are |
| + | * showjobs() -> dowait(DOWAIT_NONBLOCK) |
| + | * waitforjob(NULL) -> dowait(DOWAIT_NONBLOCK) |
| + | * waitcmd() does its own looping while it sees at least one JOBRUNNING |
| + | * job, it does not need us to loop here - only to do |
| + | * one nonblocking wait and if it gives nothing, wait for signals. |
| + | */ |
| do { | |
| pid = waitone(block, jp); | |
| rpid &= !!pid; | |
| if (!pid || (jp && jp->state != JOBRUNNING)) | |
| block = DOWAIT_NONBLOCK; | |
| - | } while (pid >= 0); |
| + | } while (pid >= 0); //WRONG? should be "pid > 0" |
| + | /* Return: 0 if seen a signal, 1 otherwise */ |
| return rpid; | |
| } | |