From 70b565bbdb911023373e035225ab10077e4ab937 Mon Sep 17 00:00:00 2001 From: Vaibhav Jain Date: Fri, 14 Oct 2016 15:08:36 +0530 Subject: cxl: Prevent adapter reset if an active context exists This patch prevents resetting the cxl adapter via sysfs in presence of one or more active cxl_context on it. This protects against an unrecoverable error caused by PSL owning a dirty cache line even after reset and host tries to touch the same cache line. In case a force reset of the card is required irrespective of any active contexts, the int value -1 can be stored in the 'reset' sysfs attribute of the card. The patch introduces a new atomic_t member named contexts_num inside struct cxl that holds the number of active context attached to the card , which is checked against '0' before proceeding with the reset. To prevent against a race condition where a context is activated just after reset check is performed, the contexts_num is atomically set to '-1' after reset-check to indicate that no more contexts can be activated on the card anymore. Before activating a context we atomically test if contexts_num is non-negative and if so, increment its value by one. In case the value of contexts_num is negative then it indicates that the card is about to be reset and context activation is error-ed out at that point. Fixes: 62fa19d4b4fd ("cxl: Add ability to reset the card") Cc: stable@vger.kernel.org # v4.0+ Acked-by: Frederic Barrat Reviewed-by: Andrew Donnellan Signed-off-by: Vaibhav Jain Signed-off-by: Michael Ellerman --- drivers/misc/cxl/file.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'drivers/misc/cxl/file.c') diff --git a/drivers/misc/cxl/file.c b/drivers/misc/cxl/file.c index 5fb9894b157f..d0b421f49b39 100644 --- a/drivers/misc/cxl/file.c +++ b/drivers/misc/cxl/file.c @@ -205,11 +205,22 @@ static long afu_ioctl_start_work(struct cxl_context *ctx, ctx->pid = get_task_pid(current, PIDTYPE_PID); ctx->glpid = get_task_pid(current->group_leader, PIDTYPE_PID); + /* + * Increment the mapped context count for adapter. This also checks + * if adapter_context_lock is taken. + */ + rc = cxl_adapter_context_get(ctx->afu->adapter); + if (rc) { + afu_release_irqs(ctx, ctx); + goto out; + } + trace_cxl_attach(ctx, work.work_element_descriptor, work.num_interrupts, amr); if ((rc = cxl_ops->attach_process(ctx, false, work.work_element_descriptor, amr))) { afu_release_irqs(ctx, ctx); + cxl_adapter_context_put(ctx->afu->adapter); goto out; } -- cgit v1.2.3