[Crash-utility] [PATCH 1/1] Fix for XArray/radix_tree rework on linux-next

[Philipp Rudo]

Commit dd12805ed1db7 ("XArray: Remove radix tree compatibility") on
linux-next changes the definition of 'radix_tree_root' back to be a struct.
The content however differs from the original 'struct radix_tree_root'.
Thus attempts to debug current linux-next kernels fail with 'radix trees do
not exist or have changed their format'. Because the new 'struct
radix_tree_root' and 'struct xarray' have nearly the same layout the
functionality for XArrays can be reused.

Signed-off-by: Philipp Rudo <prudo at linux.ibm.com>
---
 bpf.c  |  7 ++++++-
 ipcs.c |  5 ++++-
 task.c | 15 +++++++++++----
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/bpf.c b/bpf.c
index 6eacb9a..056e286 100644
--- a/bpf.c
+++ b/bpf.c
@@ -221,7 +221,12 @@ bpf_init(struct bpf_info *bpf)
 			bpf->idr_type = IDR_ORIG;
 			do_old_idr(IDR_ORIG_INIT, 0, NULL);
 		} else if (STREQ(MEMBER_TYPE_NAME("idr", "idr_rt"), "radix_tree_root"))
-			bpf->idr_type = IDR_RADIX;
+			if (MEMBER_EXISTS("radix_tree_root", "rnode"))
+				bpf->idr_type = IDR_RADIX;
+			else if (MEMBER_EXISTS("radix_tree_root", "xa_head"))
+				bpf->idr_type = IDR_XARRAY;
+			else
+				error(FATAL, "cannot determine IDR list type\n");
 		else if (STREQ(MEMBER_TYPE_NAME("idr", "idr_rt"), "xarray"))
 			bpf->idr_type = IDR_XARRAY;
 		else
diff --git a/ipcs.c b/ipcs.c
index 2553bac..3c26620 100644
--- a/ipcs.c
+++ b/ipcs.c
@@ -206,7 +206,10 @@ ipcs_init(void)
 		if (STREQ(MEMBER_TYPE_NAME("idr", "idr_rt"), "xarray"))
 			ipcs_table.init_flags |= IDR_XARRAY;
 		else
-			ipcs_table.init_flags |= IDR_RADIX;
+			if (MEMBER_EXISTS("radix_tree_root", "rnode"))
+				ipcs_table.init_flags |= IDR_RADIX;
+			else if (MEMBER_EXISTS("radix_tree_root", "xa_head"))
+				ipcs_table.init_flags |= IDR_XARRAY;
 	} else
 		ipcs_table.init_flags |= IDR_ORIG;
 
diff --git a/task.c b/task.c
index cd118e5..36a90d6 100644
--- a/task.c
+++ b/task.c
@@ -507,10 +507,17 @@ task_init(void)
 				OFFSET(pid_namespace_idr) + OFFSET(idr_idr_rt);
 			tt->flags |= PID_XARRAY;
 		} else if STREQ(MEMBER_TYPE_NAME("idr", "idr_rt"), "radix_tree_root") {
-			tt->refresh_task_table = refresh_radix_tree_task_table;
-			tt->pid_radix_tree = symbol_value("init_pid_ns") +
-				OFFSET(pid_namespace_idr) + OFFSET(idr_idr_rt);
-			tt->flags |= PID_RADIX_TREE;
+			if (MEMBER_EXISTS("radix_tree_root", "rnode")) {
+				tt->refresh_task_table = refresh_radix_tree_task_table;
+				tt->pid_radix_tree = symbol_value("init_pid_ns") +
+					OFFSET(pid_namespace_idr) + OFFSET(idr_idr_rt);
+				tt->flags |= PID_RADIX_TREE;
+			} else if (MEMBER_EXISTS("radix_tree_root", "xa_head")) {
+				tt->refresh_task_table = refresh_xarray_task_table;
+				tt->pid_xarray = symbol_value("init_pid_ns") +
+					OFFSET(pid_namespace_idr) + OFFSET(idr_idr_rt);
+				tt->flags |= PID_XARRAY;
+			}
 		} else 
 			error(FATAL, "unknown pid_namespace.idr type: %s\n",
 				MEMBER_TYPE_NAME("idr", "idr_rt"));
-- 
2.16.4