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--- a/vmmon/Makefile
+++ b/vmmon/Makefile
@@ -43,7 +43,11 @@ INCLUDE += -I$(SRCROOT)/shared
endif
+ifdef KVERSION
+VM_UNAME = $(KVERSION)
+else
VM_UNAME = $(shell uname -r)
+endif
# Header directory for the running kernel
ifdef LINUXINCLUDE
From 9fda02bce13527ce94a95df1a98fb6188dea22b8 Mon Sep 17 00:00:00 2001
From: Michal Kubecek <mkubecek@suse.cz>
Date: Wed, 30 Jun 2021 11:05:16 +0200
Subject: [PATCH] vmmon: fix task_struct::state access patterns
Mainline commit 2f064a59a11f ("sched: Change task_struct::state") in
5.14-rc1 finishes a series fixing racy access patterns to task state and
renames task_struct::state to __state so that code old code acessing it
directly fails to build.
Two of these in HostIF_SemaphoreWait() can be rewritten into calls to
set_current_state() unconditionally (second one may do with
__set_current_state() but I don't feel confident enough about that).
There are also two places where vmmon code reads task_struct::state;
provide a compat accessor using READ_ONCE() and use it instead of
a direct read. To avoid kernel version check, check presence of
get_current_state() macro introduced in the same commit as state member
rename.
---
vmmon-only/include/compat_sched.h | 15 +++++++++++++++
vmmon-only/linux/hostif.c | 10 ++++++----
2 files changed, 21 insertions(+), 4 deletions(-)
diff --git a/vmmon-only/include/compat_sched.h b/vmmon-only/include/compat_sched.h
index 3f3304b..72078e0 100644
--- a/vmmon-only/include/compat_sched.h
+++ b/vmmon-only/include/compat_sched.h
@@ -289,5 +289,20 @@ typedef struct pid * compat_pid;
#define compat_kill_pid(pid, sig, flag) kill_pid(pid, sig, flag)
#endif
+/*
+ * Since v5.14-rc1, task_struct::state hase been renamed to __state and is
+ * is longer supposed to be accessed without READ_ONCE/WRITE_ONCE.
+ */
+#ifdef get_current_state
+static inline int compat_get_task_state(const struct task_struct *t)
+{
+ return READ_ONCE(t->__state);
+}
+#else
+static inline int compat_get_task_state(const struct task_struct *t)
+{
+ return READ_ONCE(t->state);
+}
+#endif
#endif /* __COMPAT_SCHED_H__ */
diff --git a/vmmon-only/linux/hostif.c b/vmmon-only/linux/hostif.c
index 137062c..6910f69 100644
--- a/vmmon-only/linux/hostif.c
+++ b/vmmon-only/linux/hostif.c
@@ -77,6 +77,8 @@
#include "pgtbl.h"
#include "versioned_atomic.h"
+#include "compat_sched.h"
+
#if !defined(CONFIG_HIGH_RES_TIMERS)
#error CONFIG_HIGH_RES_TIMERS required for acceptable performance
#endif
@@ -474,7 +476,7 @@ HostIF_WakeUpYielders(VMDriver *vm, // IN:
ASSERT(vcpuid < vm->numVCPUs);
t = vm->vmhost->vcpuSemaTask[vcpuid];
VCPUSet_Remove(&req, vcpuid);
- if (t && (t->state & TASK_INTERRUPTIBLE)) {
+ if (t && (compat_get_task_state(t) & TASK_INTERRUPTIBLE)) {
wake_up_process(t);
}
}
@@ -2566,14 +2568,14 @@ HostIF_SemaphoreWait(VMDriver *vm, // IN:
}
poll_initwait(&table);
- current->state = TASK_INTERRUPTIBLE;
+ set_current_state(TASK_INTERRUPTIBLE);
mask = file->f_op->poll(file, &table.pt);
if (!(mask & (POLLIN | POLLERR | POLLHUP))) {
vm->vmhost->vcpuSemaTask[vcpuid] = current;
schedule_timeout(timeoutms * HZ / 1000); // convert to Hz
vm->vmhost->vcpuSemaTask[vcpuid] = NULL;
}
- current->state = TASK_RUNNING;
+ set_current_state(TASK_RUNNING);
poll_freewait(&table);
/*
@@ -2655,7 +2657,7 @@ HostIF_SemaphoreForceWakeup(VMDriver *vm, // IN:
*/
struct task_struct *t =
(struct task_struct *)xchg(&vm->vmhost->vcpuSemaTask[vcpuid], NULL);
- if (t && (t->state & TASK_INTERRUPTIBLE)) {
+ if (t && (compat_get_task_state(t) & TASK_INTERRUPTIBLE)) {
wake_up_process(t);
}
} ROF_EACH_VCPU_IN_SET_WITH_MAX();
|