cxl_ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
}
+/*
+ * Returns the mm_struct corresponding to the context ctx via ctx->pid
+ * In case the task has exited we use the task group leader accessible
+ * via ctx->glpid to find the next task in the thread group that has a
+ * valid mm_struct associated with it. If a task with valid mm_struct
+ * is found the ctx->pid is updated to use the task struct for subsequent
+ * translations. In case no valid mm_struct is found in the task group to
+ * service the fault a NULL is returned.
+ */
+static struct mm_struct *get_mem_context(struct cxl_context *ctx)
+{
+ struct task_struct *task = NULL;
+ struct mm_struct *mm = NULL;
+ struct pid *old_pid = ctx->pid;
+
+ if (old_pid == NULL) {
+ pr_warn("%s: Invalid context for pe=%d\n",
+ __func__, ctx->pe);
+ return NULL;
+ }
+
+ task = get_pid_task(old_pid, PIDTYPE_PID);
+
+ /*
+ * pid_alive may look racy but this saves us from costly
+ * get_task_mm when the task is a zombie. In worst case
+ * we may think a task is alive, which is about to die
+ * but get_task_mm will return NULL.
+ */
+ if (task != NULL && pid_alive(task))
+ mm = get_task_mm(task);
+
+ /* release the task struct that was taken earlier */
+ if (task)
+ put_task_struct(task);
+ else
+ pr_devel("%s: Context owning pid=%i for pe=%i dead\n",
+ __func__, pid_nr(old_pid), ctx->pe);
+
+ /*
+ * If we couldn't find the mm context then use the group
+ * leader to iterate over the task group and find a task
+ * that gives us mm_struct.
+ */
+ if (unlikely(mm == NULL && ctx->glpid != NULL)) {
+
+ rcu_read_lock();
+ task = pid_task(ctx->glpid, PIDTYPE_PID);
+ if (task)
+ do {
+ mm = get_task_mm(task);
+ if (mm) {
+ ctx->pid = get_task_pid(task,
+ PIDTYPE_PID);
+ break;
+ }
+ task = next_thread(task);
+ } while (task && !thread_group_leader(task));
+ rcu_read_unlock();
+
+ /* check if we switched pid */
+ if (ctx->pid != old_pid) {
+ if (mm)
+ pr_devel("%s:pe=%i switch pid %i->%i\n",
+ __func__, ctx->pe, pid_nr(old_pid),
+ pid_nr(ctx->pid));
+ else
+ pr_devel("%s:Cannot find mm for pid=%i\n",
+ __func__, pid_nr(old_pid));
+
+ /* drop the reference to older pid */
+ put_pid(old_pid);
+ }
+ }
+
+ return mm;
+}
+
+
+
void cxl_handle_fault(struct work_struct *fault_work)
{
struct cxl_context *ctx =
container_of(fault_work, struct cxl_context, fault_work);
u64 dsisr = ctx->dsisr;
u64 dar = ctx->dar;
- struct task_struct *task = NULL;
struct mm_struct *mm = NULL;
if (cxl_p2n_read(ctx->afu, CXL_PSL_DSISR_An) != dsisr ||
"DSISR: %#llx DAR: %#llx\n", ctx->pe, dsisr, dar);
if (!ctx->kernel) {
- if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) {
- pr_devel("cxl_handle_fault unable to get task %i\n",
- pid_nr(ctx->pid));
+
+ mm = get_mem_context(ctx);
+ /* indicates all the thread in task group have exited */
+ if (mm == NULL) {
+ pr_devel("%s: unable to get mm for pe=%d pid=%i\n",
+ __func__, ctx->pe, pid_nr(ctx->pid));
cxl_ack_ae(ctx);
return;
- }
- if (!(mm = get_task_mm(task))) {
- pr_devel("cxl_handle_fault unable to get mm %i\n",
- pid_nr(ctx->pid));
- cxl_ack_ae(ctx);
- goto out;
+ } else {
+ pr_devel("Handling page fault for pe=%d pid=%i\n",
+ ctx->pe, pid_nr(ctx->pid));
}
}
if (mm)
mmput(mm);
-out:
- if (task)
- put_task_struct(task);
}
static void cxl_prefault_one(struct cxl_context *ctx, u64 ea)
{
- int rc;
- struct task_struct *task;
struct mm_struct *mm;
- if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) {
- pr_devel("cxl_prefault_one unable to get task %i\n",
- pid_nr(ctx->pid));
- return;
- }
- if (!(mm = get_task_mm(task))) {
+ mm = get_mem_context(ctx);
+ if (mm == NULL) {
pr_devel("cxl_prefault_one unable to get mm %i\n",
pid_nr(ctx->pid));
- put_task_struct(task);
return;
}
- rc = cxl_fault_segment(ctx, mm, ea);
+ cxl_fault_segment(ctx, mm, ea);
mmput(mm);
- put_task_struct(task);
}
static u64 next_segment(u64 ea, u64 vsid)
struct copro_slb slb;
struct vm_area_struct *vma;
int rc;
- struct task_struct *task;
struct mm_struct *mm;
- if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) {
- pr_devel("cxl_prefault_vma unable to get task %i\n",
- pid_nr(ctx->pid));
- return;
- }
- if (!(mm = get_task_mm(task))) {
+ mm = get_mem_context(ctx);
+ if (mm == NULL) {
pr_devel("cxl_prefault_vm unable to get mm %i\n",
pid_nr(ctx->pid));
- goto out1;
+ return;
}
down_read(&mm->mmap_sem);
up_read(&mm->mmap_sem);
mmput(mm);
-out1:
- put_task_struct(task);
}
void cxl_prefault(struct cxl_context *ctx, u64 wed)
Code Review / kvmfornfv.git / blobdiff