Mercurial > hg > nginx
view src/os/unix/rfork_thread.S @ 3440:88741ec7731a stable-0.7
merge r3294, r3305:
Fix a bug introduced in r2032: After a child process has read a terminate
message from a channel, the process tries to read the channel again.
The kernel (at least FreeBSD) may preempt the process and sends a SIGIO
signal to a master process. The master process sends a new terminate message,
the kernel switches again to the the child process, and the child process
reads the messages instead of an EAGAIN error. And this may repeat over
and over. Being that the child process can not exit the cycle and test
the termination flag set by the message handler.
The fix disallow the master process to send a new terminate message on
SIGIO signal reception. It may send the message only on SIGALARM signal.
author | Igor Sysoev <igor@sysoev.ru> |
---|---|
date | Mon, 01 Feb 2010 15:49:36 +0000 |
parents | 621229427cba |
children | d620f497c50f |
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/* * Copyright (C) Igor Sysoev */ #include <sys/syscall.h> #include <machine/asm.h> /* * rfork_thread(3) - rfork_thread(flags, stack, func, arg); */ #define KERNCALL int $0x80 ENTRY(rfork_thread) push %ebp mov %esp, %ebp push %esi mov 12(%ebp), %esi # the thread stack address sub $4, %esi mov 20(%ebp), %eax # the thread argument mov %eax, (%esi) sub $4, %esi mov 16(%ebp), %eax # the thread start address mov %eax, (%esi) push 8(%ebp) # rfork(2) flags push $0 mov $SYS_rfork, %eax KERNCALL jc error cmp $0, %edx jne child parent: add $8, %esp pop %esi leave ret child: mov %esi, %esp pop %eax call *%eax # call a thread start address ... add $4, %esp push %eax push $0 mov $SYS_exit, %eax # ... and exit(2) after a thread would return KERNCALL error: add $8, %esp pop %esi leave PIC_PROLOGUE /* libc's cerror: jmp PIC_PLT(HIDENAME(cerror)) */ push %eax call PIC_PLT(CNAME(__error)) pop %ecx PIC_EPILOGUE mov %ecx, (%eax) mov $-1, %eax mov $-1, %edx ret