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[PULL 40/42] bsd-user: Implement interlock for atomic operations
From: |
imp |
Subject: |
[PULL 40/42] bsd-user: Implement interlock for atomic operations |
Date: |
Tue, 7 Sep 2021 15:53:30 -0600 |
From: Warner Losh <imp@FreeBSD.org>
Implement the internlock in fork_start() and fork_end() to properly cope
with atomic operations and to safely keep state for parent and child
processes.
Signed-off-by: Stacey Son <sson@FreeBSD.org>
Signed-off-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
bsd-user/main.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/bsd-user/main.c b/bsd-user/main.c
index 768f4ee41e..659dd2b512 100644
--- a/bsd-user/main.c
+++ b/bsd-user/main.c
@@ -69,15 +69,39 @@ unsigned long target_dflssiz = TARGET_DFLSSIZ; /* initial
data size limit */
unsigned long target_maxssiz = TARGET_MAXSSIZ; /* max stack size */
unsigned long target_sgrowsiz = TARGET_SGROWSIZ; /* amount to grow stack */
+/* Helper routines for implementing atomic operations. */
void fork_start(void)
{
+ start_exclusive();
+ cpu_list_lock();
+ mmap_fork_start();
}
void fork_end(int child)
{
if (child) {
+ CPUState *cpu, *next_cpu;
+ /*
+ * Child processes created by fork() only have a single thread.
Discard
+ * information about the parent threads.
+ */
+ CPU_FOREACH_SAFE(cpu, next_cpu) {
+ if (cpu != thread_cpu) {
+ QTAILQ_REMOVE_RCU(&cpus, cpu, node);
+ }
+ }
+ mmap_fork_end(child);
+ /*
+ * qemu_init_cpu_list() takes care of reinitializing the exclusive
+ * state, so we don't need to end_exclusive() here.
+ */
+ qemu_init_cpu_list();
gdbserver_fork(thread_cpu);
+ } else {
+ mmap_fork_end(child);
+ cpu_list_unlock();
+ end_exclusive();
}
}
--
2.32.0
- [PULL 11/42] bsd-user: Eliminate elf personality, (continued)
- [PULL 11/42] bsd-user: Eliminate elf personality, imp, 2021/09/07
- [PULL 24/42] bsd-user: Create target specific vmparam.h, imp, 2021/09/07
- [PULL 20/42] bsd-user: Move per-cpu code into target_arch_cpu.h, imp, 2021/09/07
- [PULL 31/42] bsd-user: Remove dead #ifdefs from elfload.c, imp, 2021/09/07
- [PULL 33/42] bsd-user: update debugging in mmap.c, imp, 2021/09/07
- [PULL 36/42] bsd-user: add stubbed out core dump support, imp, 2021/09/07
- [PULL 35/42] bsd-user: Add target_os_user.h to capture the user/kernel structures, imp, 2021/09/07
- [PULL 39/42] bsd-user: move gemu_log to later in the file, imp, 2021/09/07
- [PULL 34/42] bsd-user: Add target_arch_reg to describe a target's register set, imp, 2021/09/07
- [PULL 38/42] bsd-user: Refactor load_elf_sections and is_target_elf_binary, imp, 2021/09/07
- [PULL 40/42] bsd-user: Implement interlock for atomic operations,
imp <=
- [PULL 41/42] bsd-user: Add '-0 argv0' option to bsd-user/main.c, imp, 2021/09/07
- [PULL 37/42] bsd-user: elfload.c style catch up patch, imp, 2021/09/07
- [PULL 28/42] bsd-user: Move stack initializtion into a per-os file., imp, 2021/09/07
- [PULL 42/42] bsd-user: Update mapping to handle reserved and starting conditions, imp, 2021/09/07
- Re: [PULL 00/42] bsd-user updates to run hello world, Peter Maydell, 2021/09/09
- Re: [PULL 00/42] bsd-user updates to run hello world, Philippe Mathieu-Daudé, 2021/09/09