From 1b5df59e50874b9034c0fa389cd52b65f1f93292 Mon Sep 17 00:00:00 2001 From: Vaibhav Jain Date: Mon, 16 Nov 2015 09:33:45 +0530 Subject: cxl: Fix possible idr warning when contexts are released An idr warning is reported when a context is release after the capi card is unbound from the cxl driver via sysfs. Below are the steps to reproduce: 1. Create multiple afu contexts in an user-space application using libcxl. 2. Unbind capi card from cxl using command of form echo > /sys/bus/pci/drivers/cxl-pci/unbind 3. Exit/kill the application owning afu contexts. After above steps a warning message is usually seen in the kernel logs of the form "idr_remove called for id= which is not allocated." This is caused by the function cxl_release_afu which destroys the contexts_idr table. So when a context is release no entry for context pe is found in the contexts_idr table and idr code prints this warning. This patch fixes this issue by increasing & decreasing the ref-count on the afu device when a context is initialized or when its freed respectively. This prevents the afu from being released until all the afu contexts have been released. The patch introduces two new functions namely cxl_afu_get/put that manage the ref-count on the afu device. Also the patch removes code inside cxl_dev_context_init that increases ref on the afu device as its guaranteed to be alive during this function. Reported-by: Ian Munsie Signed-off-by: Vaibhav Jain Acked-by: Ian Munsie Signed-off-by: Michael Ellerman --- drivers/misc/cxl/api.c | 4 ---- 1 file changed, 4 deletions(-) (limited to 'drivers/misc/cxl/api.c') diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c index 103baf0e0c5b..a6543aefa299 100644 --- a/drivers/misc/cxl/api.c +++ b/drivers/misc/cxl/api.c @@ -25,7 +25,6 @@ struct cxl_context *cxl_dev_context_init(struct pci_dev *dev) afu = cxl_pci_to_afu(dev); - get_device(&afu->dev); ctx = cxl_context_alloc(); if (IS_ERR(ctx)) { rc = PTR_ERR(ctx); @@ -61,7 +60,6 @@ err_mapping: err_ctx: kfree(ctx); err_dev: - put_device(&afu->dev); return ERR_PTR(rc); } EXPORT_SYMBOL_GPL(cxl_dev_context_init); @@ -87,8 +85,6 @@ int cxl_release_context(struct cxl_context *ctx) if (ctx->status >= STARTED) return -EBUSY; - put_device(&ctx->afu->dev); - cxl_context_free(ctx); return 0; -- cgit v1.2.3 From 7b8ad495d59280b634a7b546f4cdf58cf4d65f61 Mon Sep 17 00:00:00 2001 From: Vaibhav Jain Date: Tue, 24 Nov 2015 16:26:18 +0530 Subject: cxl: Fix DSI misses when the context owning task exits Presently when a user-space process issues CXL_IOCTL_START_WORK ioctl we store the pid of the current task_struct and use it to get pointer to the mm_struct of the process, while processing page or segment faults from the capi card. However this causes issues when the thread that had originally issued the start-work ioctl exits in which case the stored pid is no more valid and the cxl driver is unable to handle faults as the mm_struct corresponding to process is no more accessible. This patch fixes this issue by using the mm_struct of the next alive task in the thread group. This is done by iterating over all the tasks in the thread group starting from thread group leader and calling get_task_mm on each one of them. When a valid mm_struct is obtained the pid of the associated task is stored in the context replacing the exiting one for handling future faults. The patch introduces a new function named get_mem_context that checks if the current task pointed to by ctx->pid is dead? If yes it performs the steps described above. Also a new variable cxl_context.glpid is introduced which stores the pid of the thread group leader associated with the context owning task. Reported-by: Matthew R. Ochs Reported-by: Frank Haverkamp Suggested-by: Ian Munsie Signed-off-by: Vaibhav Jain Acked-by: Ian Munsie Reviewed-by: Frederic Barrat Reviewed-by: Matthew R. Ochs Signed-off-by: Michael Ellerman --- drivers/misc/cxl/api.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/misc/cxl/api.c') diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c index a6543aefa299..ea3eeb7011e1 100644 --- a/drivers/misc/cxl/api.c +++ b/drivers/misc/cxl/api.c @@ -172,7 +172,7 @@ int cxl_start_context(struct cxl_context *ctx, u64 wed, if (task) { ctx->pid = get_task_pid(task, PIDTYPE_PID); - get_pid(ctx->pid); + ctx->glpid = get_task_pid(task->group_leader, PIDTYPE_PID); kernel = false; } -- cgit v1.2.3