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authorFrederic Barrat <fbarrat@linux.vnet.ibm.com>2017-08-30 12:15:49 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-10-05 09:41:47 +0200
commit6124ed1a712a2dc886abb826748a7a3254186c6c (patch)
tree1804ac8b0bf9a2e40f1857b6353c4768d81d6bdc
parent9037837e0c32f2a90fbd0824f271b23d49e3eb35 (diff)
cxl: Fix driver use count
commit 197267d0356004a31c4d6b6336598f5dff3301e1 upstream. cxl keeps a driver use count, which is used with the hash memory model on p8 to know when to upgrade local TLBIs to global and to trigger callbacks to manage the MMU for PSL8. If a process opens a context and closes without attaching or fails the attachment, the driver use count is never decremented. As a consequence, TLB invalidations remain global, even if there are no active cxl contexts. We should increment the driver use count when the process is attaching to the cxl adapter, and not on open. It's not needed before the adapter starts using the context and the use count is decremented on the detach path, so it makes more sense. It affects only the user api. The kernel api is already doing The Right Thing. Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com> Fixes: 7bb5d91a4dda ("cxl: Rework context lifetimes") Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> [ajd: backport to stable v4.4 tree] Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/misc/cxl/api.c4
-rw-r--r--drivers/misc/cxl/file.c8
2 files changed, 11 insertions, 1 deletions
diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
index ea3eeb7011e1..690eb1a18caf 100644
--- a/drivers/misc/cxl/api.c
+++ b/drivers/misc/cxl/api.c
@@ -176,6 +176,10 @@ int cxl_start_context(struct cxl_context *ctx, u64 wed,
kernel = false;
}
+ /*
+ * Increment driver use count. Enables global TLBIs for hash
+ * and callbacks to handle the segment table
+ */
cxl_ctx_get();
if ((rc = cxl_attach_process(ctx, kernel, wed , 0))) {
diff --git a/drivers/misc/cxl/file.c b/drivers/misc/cxl/file.c
index 10a02934bfc0..013558f4da4f 100644
--- a/drivers/misc/cxl/file.c
+++ b/drivers/misc/cxl/file.c
@@ -94,7 +94,6 @@ static int __afu_open(struct inode *inode, struct file *file, bool master)
pr_devel("afu_open pe: %i\n", ctx->pe);
file->private_data = ctx;
- cxl_ctx_get();
/* indicate success */
rc = 0;
@@ -205,11 +204,18 @@ 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 driver use count. Enables global TLBIs for hash
+ * and callbacks to handle the segment table
+ */
+ cxl_ctx_get();
+
trace_cxl_attach(ctx, work.work_element_descriptor, work.num_interrupts, amr);
if ((rc = cxl_attach_process(ctx, false, work.work_element_descriptor,
amr))) {
afu_release_irqs(ctx, ctx);
+ cxl_ctx_put();
goto out;
}