include/user/safe-syscall.h

2  * safe-syscall.h: prototypes for linux-user signal-race-safe syscalls
26  * Call a system call if guest signal not pending.
28  * may return -1 with errno == QEMU_ERESTARTSYS if a signal was pending.
48  * a little less efficient if a signal is delivered at the 'wrong' moment.
54  * all syscalls which change the thread's signal mask.
72  * signal could arrive just before we make the host syscall inside libc,
93  * section of host native assembly. If a signal occurs, our signal
97  * -QEMU_ERESTARTSYS" code path instead, and then exit the signal handler
101  * the guest signal handler as usual.
104  * (1) signal came in just before we took the host syscall (a race);
105  *   in this case we'll take the guest signal and have another go
108  *   signal really did win the race
109  * (2) signal came in while the host syscall was blocking, and the
113  *   "first call the signal handler, then reattempt the syscall".)
114  * The other situation to consider is when a signal came in while the
116  * should not be restarted; in this case QEMU's host signal handler will