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kernel: fix race condition in input component

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Benji Dial 2025-12-28 20:27:00 -05:00
parent e2188aa407
commit e698cfdfd1
4 changed files with 27 additions and 2 deletions
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7
src/kernel/input.c
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@ -38,6 +38,7 @@ void add_mouse_movement(int x, int y) {
add_to_queue(&ready_continuations, &waiting_continuation); add_to_queue(&ready_continuations, &waiting_continuation);
total_unreported_x_movement = 0; total_unreported_x_movement = 0;
total_unreported_y_movement = 0; total_unreported_y_movement = 0;
is_somebody_waiting_for_mouse_packet = 0;
} }
} }
@ -46,6 +47,8 @@ void syscall_wait_for_mouse_packet(struct mouse_packet *packet_out) {
assert(running_thread != 0); assert(running_thread != 0);
__asm__ ("cli");
//TODO: handle these //TODO: handle these
if (is_somebody_waiting_for_mouse_packet || if (is_somebody_waiting_for_mouse_packet ||
!is_mapped_writable( !is_mapped_writable(
@ -57,12 +60,12 @@ void syscall_wait_for_mouse_packet(struct mouse_packet *packet_out) {
packet_out->y_change = total_unreported_y_movement; packet_out->y_change = total_unreported_y_movement;
total_unreported_x_movement = 0; total_unreported_x_movement = 0;
total_unreported_y_movement = 0; total_unreported_y_movement = 0;
__asm__ ("sti");
return; return;
} }
is_somebody_waiting_for_mouse_packet = 1; is_somebody_waiting_for_mouse_packet = 1;
resume_by_reporting_to = packet_out; resume_by_reporting_to = packet_out;
yield(&waiting_continuation); yield_sti(&waiting_continuation);
is_somebody_waiting_for_mouse_packet = 0;
} }

1
src/kernel/input.h
View file

@ -19,6 +19,7 @@
#include <kernel-public/input.h> #include <kernel-public/input.h>
//should only be called with interrupts disabled
void add_mouse_movement(int x, int y); void add_mouse_movement(int x, int y);
void syscall_wait_for_mouse_packet(struct mouse_packet *packet_out); void syscall_wait_for_mouse_packet(struct mouse_packet *packet_out);

18
src/kernel/scheduler.asm
View file

@ -53,3 +53,21 @@ yield:
.ret: .ret:
ret ret
global yield_sti
yield_sti:
mov qword [rdi], ret
mov qword [rdi + 8], rbx
mov qword [rdi + 16], rbp
mov qword [rdi + 24], rsp
mov qword [rdi + 32], r12
mov qword [rdi + 40], r13
mov qword [rdi + 48], r14
mov qword [rdi + 56], r15
sti
jmp resume_next_continuation
.ret:
ret

3
src/kernel/scheduler.h
View file

@ -54,3 +54,6 @@ int take_from_queue(struct continuation_queue *queue, struct continuation_info *
//saves a continuation that returns from this function to save_current_continuation_to, then resumes //saves a continuation that returns from this function to save_current_continuation_to, then resumes
//the next ready continuation (thus doesn't return until save_current_continuation_to is resumed). //the next ready continuation (thus doesn't return until save_current_continuation_to is resumed).
void yield(struct continuation_info *save_current_continuation_to); void yield(struct continuation_info *save_current_continuation_to);
//save as yield but enables interrupts between saving this continuation and resuming next ready one.
void yield_sti(struct continuation_info *save_current_continuation_to);