From 7077d71d4640a38f86bbc9815f7a5489eb8d9453 Mon Sep 17 00:00:00 2001
From: acevest <zhaoyanbai@126.com>
Date: Sat, 11 May 2024 13:39:53 +0800
Subject: [PATCH] =?utf8?q?=E7=A7=BB=E9=99=A4reenter=E7=9A=84=E7=BD=97?=
 =?utf8?q?=E8=BE=91,=E7=94=A8=E5=88=A4=E6=96=AD=E6=98=AF=E5=90=A6=E5=9C=A8?=
 =?utf8?q?=E5=BA=95=E5=8D=8A=E5=A4=84=E7=90=86=E7=9A=84=E6=96=B9=E5=BC=8F?=
 =?utf8?q?=E6=9B=BF=E4=BB=A3?=
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---
 include/irq.h    |  2 ++
 include/system.h |  4 +---
 kernel/clock.c   |  5 ++++-
 kernel/irq.c     | 19 ++++++++++++-------
 kernel/syscall.S |  1 -
 kernel/system.c  |  2 --
 6 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/include/irq.h b/include/irq.h
index bec6002..c72dcdc 100644
--- a/include/irq.h
+++ b/include/irq.h
@@ -81,4 +81,6 @@ bool irq_disabled();
 #define IRQ_CASCADE 0x02
 #define IRQ_DISK 0x0E
 
+bool in_bh();
+
 #endif  //_IRQ_H
diff --git a/include/system.h b/include/system.h
index 9189c40..b4d3f01 100644
--- a/include/system.h
+++ b/include/system.h
@@ -77,7 +77,7 @@ extern char etext, edata, end;
 #define disableIRQ() cli()
 #define enableIRQ() sti()
 
-#define ALIGN(x, a) (((x) + (a)-1) & ~((a)-1))
+#define ALIGN(x, a) (((x) + (a) - 1) & ~((a) - 1))
 
 // 定义最大显存为 16MB
 #define VRAM_VADDR_SIZE (16 << 20)
@@ -264,8 +264,6 @@ void init_task_entry();
 void disk_task_entry();
 void user_task_entry();
 
-extern volatile int reenter;
-
 #define DEFAULT_BOOT_DELAY_TICKS 30
 void boot_delay(int ticks);
 
diff --git a/kernel/clock.c b/kernel/clock.c
index e78622f..b2601f1 100644
--- a/kernel/clock.c
+++ b/kernel/clock.c
@@ -42,6 +42,7 @@ void clk_handler(unsigned int irq, pt_regs_t *regs, void *dev_id) {
     // 打断后该时钟中断不应该继续减少该进程的时间片，因为这会造成该进程在后续的调底中少了实际的运行时间
     if (1 == current->need_resched) {
         // 这种情况必然已经发生了该时钟中断打断了下半部处理程序
+        // 反之时钟中断打断了下半部处理程序不一定need_resched就为1
         return;
     }
 
@@ -55,7 +56,9 @@ void clk_handler(unsigned int irq, pt_regs_t *regs, void *dev_id) {
 
     assert(current->ticks >= 0);  // 防止ticks被减到0后再减溢出
 
-    add_irq_bh_handler(clk_bh_handler, NULL);
+    if (!in_bh()) {
+        add_irq_bh_handler(clk_bh_handler, NULL);
+    }
 }
 
 // 开中断执行这个函数
diff --git a/kernel/irq.c b/kernel/irq.c
index b25f382..1c462e3 100644
--- a/kernel/irq.c
+++ b/kernel/irq.c
@@ -77,6 +77,12 @@ void dump_irq_nr_stack() {
 void irq_bh_handler();
 void schedule();
 
+volatile bool in_bh_logic = false;
+
+volatile uint32_t reenter_count = 0;
+
+bool in_bh() { return in_bh_logic; }
+
 __attribute__((regparm(1))) void irq_handler(pt_regs_t *regs) {
     unsigned int irq = regs->irq;
     if (irq >= NR_IRQS) {
@@ -87,7 +93,6 @@ __attribute__((regparm(1))) void irq_handler(pt_regs_t *regs) {
     irq_action_t *action = p->action;
 
     assert(irq_disabled());
-    reenter++;
 
     // 屏蔽当前中断
     p->chip->disable(irq);
@@ -100,8 +105,8 @@ __attribute__((regparm(1))) void irq_handler(pt_regs_t *regs) {
 #if 1
     unsigned long esp;
     asm("movl %%esp, %%eax" : "=a"(esp));
-    printl(MPL_CURRENT, "current %08x %-6s cr3 %08x reenter %d esp %08x ticks %u", current, current->name, current->cr3,
-           reenter, esp, current->ticks);
+    printl(MPL_CURRENT, "current %08x %-6s cr3 %08x esp %08x reenter %u ticks %u", current, current->name, current->cr3,
+           esp, reenter_count, current->ticks);
 #endif
 
     while (action && action->handler) {
@@ -115,25 +120,25 @@ __attribute__((regparm(1))) void irq_handler(pt_regs_t *regs) {
     // 代表当前中断程序打断了前一个中断程序的“开中断处理的底半部分逻辑”
     // 即前一个中断处理尚未完全完成
     assert(irq_disabled());
-    if (reenter != 0) {
-        reenter--;
+    if (in_bh_logic) {
+        reenter_count++;
         return;
     }
     // --以上逻辑CPU处于中断禁止状态--------------------------
 
     // 此处执行中断函数的下半部分逻辑，开中断执行
     {
+        in_bh_logic = true;
         enable_irq();
 
         irq_bh_handler();
 
         disable_irq();
+        in_bh_logic = false;
     }
 
     // --以下逻辑CPU处于中断禁止状态--------------------------
     assert(irq_disabled());
-    assert(reenter == 0);
-    reenter--;
 
     // 考察如果不需要调度程序，直接退出
     if (current->need_resched == 0) {
diff --git a/kernel/syscall.S b/kernel/syscall.S
index 3b9b27f..9c8f01b 100644
--- a/kernel/syscall.S
+++ b/kernel/syscall.S
@@ -26,7 +26,6 @@
 .text
 .global syscall_entry
 .global ret_from_fork_krnl
-.extern reenter
 //.global syscall_exit
 
 syscall_entry:
diff --git a/kernel/system.c b/kernel/system.c
index 1717762..da11654 100644
--- a/kernel/system.c
+++ b/kernel/system.c
@@ -36,8 +36,6 @@ char idtr[6] __attribute__((__aligned__(4)));
 extern char _gdtr[6];
 extern char _idtr[6];
 
-volatile int reenter = -1;
-
 void setup_gdt() {
     pDesc pdesc;
     // change to new gdt.
-- 
2.44.0