diff options
| -rw-r--r-- | drivers/misc/cxl/api.c | 17 | ||||
| -rw-r--r-- | drivers/misc/cxl/context.c | 21 | ||||
| -rw-r--r-- | drivers/misc/cxl/cxl.h | 10 | ||||
| -rw-r--r-- | drivers/misc/cxl/fault.c | 76 | ||||
| -rw-r--r-- | drivers/misc/cxl/file.c | 15 | ||||
| -rw-r--r-- | drivers/misc/cxl/main.c | 12 |
6 files changed, 61 insertions, 90 deletions
diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c index bcc030eacab7..1a138c83f877 100644 --- a/drivers/misc/cxl/api.c +++ b/drivers/misc/cxl/api.c @@ -14,6 +14,7 @@ #include <linux/msi.h> #include <linux/module.h> #include <linux/mount.h> +#include <linux/sched/mm.h> #include "cxl.h" @@ -321,19 +322,29 @@ int cxl_start_context(struct cxl_context *ctx, u64 wed, if (task) { ctx->pid = get_task_pid(task, PIDTYPE_PID); - ctx->glpid = get_task_pid(task->group_leader, PIDTYPE_PID); kernel = false; ctx->real_mode = false; + + /* acquire a reference to the task's mm */ + ctx->mm = get_task_mm(current); + + /* ensure this mm_struct can't be freed */ + cxl_context_mm_count_get(ctx); + + /* decrement the use count */ + if (ctx->mm) + mmput(ctx->mm); } cxl_ctx_get(); if ((rc = cxl_ops->attach_process(ctx, kernel, wed, 0))) { - put_pid(ctx->glpid); put_pid(ctx->pid); - ctx->glpid = ctx->pid = NULL; + ctx->pid = NULL; cxl_adapter_context_put(ctx->afu->adapter); cxl_ctx_put(); + if (task) + cxl_context_mm_count_put(ctx); goto out; } diff --git a/drivers/misc/cxl/context.c b/drivers/misc/cxl/context.c index 062bf6ca2625..2e935eadee80 100644 --- a/drivers/misc/cxl/context.c +++ b/drivers/misc/cxl/context.c @@ -17,6 +17,7 @@ #include <linux/debugfs.h> #include <linux/slab.h> #include <linux/idr.h> +#include <linux/sched/mm.h> #include <asm/cputable.h> #include <asm/current.h> #include <asm/copro.h> @@ -41,7 +42,7 @@ int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master) spin_lock_init(&ctx->sste_lock); ctx->afu = afu; ctx->master = master; - ctx->pid = ctx->glpid = NULL; /* Set in start work ioctl */ + ctx->pid = NULL; /* Set in start work ioctl */ mutex_init(&ctx->mapping_lock); ctx->mapping = NULL; @@ -242,12 +243,16 @@ int __detach_context(struct cxl_context *ctx) /* release the reference to the group leader and mm handling pid */ put_pid(ctx->pid); - put_pid(ctx->glpid); cxl_ctx_put(); /* Decrease the attached context count on the adapter */ cxl_adapter_context_put(ctx->afu->adapter); + + /* Decrease the mm count on the context */ + cxl_context_mm_count_put(ctx); + ctx->mm = NULL; + return 0; } @@ -325,3 +330,15 @@ void cxl_context_free(struct cxl_context *ctx) mutex_unlock(&ctx->afu->contexts_lock); call_rcu(&ctx->rcu, reclaim_ctx); } + +void cxl_context_mm_count_get(struct cxl_context *ctx) +{ + if (ctx->mm) + atomic_inc(&ctx->mm->mm_count); +} + +void cxl_context_mm_count_put(struct cxl_context *ctx) +{ + if (ctx->mm) + mmdrop(ctx->mm); +} diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h index 36bc213629ad..4bcbf7a9bba6 100644 --- a/drivers/misc/cxl/cxl.h +++ b/drivers/misc/cxl/cxl.h @@ -482,8 +482,6 @@ struct cxl_context { unsigned int sst_size, sst_lru; wait_queue_head_t wq; - /* pid of the group leader associated with the pid */ - struct pid *glpid; /* use mm context associated with this pid for ds faults */ struct pid *pid; spinlock_t lock; /* Protects pending_irq_mask, pending_fault and fault_addr */ @@ -551,6 +549,8 @@ struct cxl_context { * CX4 only: */ struct list_head extra_irq_contexts; + + struct mm_struct *mm; }; struct cxl_service_layer_ops { @@ -1012,4 +1012,10 @@ int cxl_adapter_context_lock(struct cxl *adapter); /* Unlock the contexts-lock if taken. Warn and force unlock otherwise */ void cxl_adapter_context_unlock(struct cxl *adapter); +/* Increases the reference count to "struct mm_struct" */ +void cxl_context_mm_count_get(struct cxl_context *ctx); + +/* Decrements the reference count to "struct mm_struct" */ +void cxl_context_mm_count_put(struct cxl_context *ctx); + #endif diff --git a/drivers/misc/cxl/fault.c b/drivers/misc/cxl/fault.c index 2fa015c05561..e6f8f05446be 100644 --- a/drivers/misc/cxl/fault.c +++ b/drivers/misc/cxl/fault.c @@ -170,81 +170,18 @@ static void cxl_handle_page_fault(struct cxl_context *ctx, } /* - * 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. + * Returns the mm_struct corresponding to the context ctx. + * mm_users == 0, the context may be in the process of being closed. */ 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); + if (ctx->mm == NULL) 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); - } - } + if (!atomic_inc_not_zero(&ctx->mm->mm_users)) + return NULL; - return mm; + return ctx->mm; } @@ -282,7 +219,6 @@ void cxl_handle_fault(struct work_struct *fault_work) if (!ctx->kernel) { 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)); diff --git a/drivers/misc/cxl/file.c b/drivers/misc/cxl/file.c index e7139c76f961..17b433f1ce23 100644 --- a/drivers/misc/cxl/file.c +++ b/drivers/misc/cxl/file.c @@ -18,6 +18,7 @@ #include <linux/fs.h> #include <linux/mm.h> #include <linux/slab.h> +#include <linux/sched/mm.h> #include <asm/cputable.h> #include <asm/current.h> #include <asm/copro.h> @@ -216,8 +217,16 @@ static long afu_ioctl_start_work(struct cxl_context *ctx, * process is still accessible. */ ctx->pid = get_task_pid(current, PIDTYPE_PID); - ctx->glpid = get_task_pid(current->group_leader, PIDTYPE_PID); + /* acquire a reference to the task's mm */ + ctx->mm = get_task_mm(current); + + /* ensure this mm_struct can't be freed */ + cxl_context_mm_count_get(ctx); + + /* decrement the use count */ + if (ctx->mm) + mmput(ctx->mm); trace_cxl_attach(ctx, work.work_element_descriptor, work.num_interrupts, amr); @@ -225,9 +234,9 @@ static long afu_ioctl_start_work(struct cxl_context *ctx, amr))) { afu_release_irqs(ctx, ctx); cxl_adapter_context_put(ctx->afu->adapter); - put_pid(ctx->glpid); put_pid(ctx->pid); - ctx->glpid = ctx->pid = NULL; + ctx->pid = NULL; + cxl_context_mm_count_put(ctx); goto out; } diff --git a/drivers/misc/cxl/main.c b/drivers/misc/cxl/main.c index b0b6ed31918e..1703655072b1 100644 --- a/drivers/misc/cxl/main.c +++ b/drivers/misc/cxl/main.c @@ -59,16 +59,10 @@ int cxl_afu_slbia(struct cxl_afu *afu) static inline void _cxl_slbia(struct cxl_context *ctx, struct mm_struct *mm) { - struct task_struct *task; unsigned long flags; - if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) { - pr_devel("%s unable to get task %i\n", - __func__, pid_nr(ctx->pid)); - return; - } - if (task->mm != mm) - goto out_put; + if (ctx->mm != mm) + return; pr_devel("%s matched mm - card: %i afu: %i pe: %i\n", __func__, ctx->afu->adapter->adapter_num, ctx->afu->slice, ctx->pe); @@ -79,8 +73,6 @@ static inline void _cxl_slbia(struct cxl_context *ctx, struct mm_struct *mm) spin_unlock_irqrestore(&ctx->sste_lock, flags); mb(); cxl_afu_slbia(ctx->afu); -out_put: - put_task_struct(task); } static inline void cxl_slbia_core(struct mm_struct *mm) |