Hi Matthew, > > Because the radix tree seems to have no dedicated tree nor maintainer, I > > suggest that all these patches go in via hwspinlock. This also keeps the > > dependencies zero. > > The radix tree is deprecated. I don't want to add any new functionality > to it. Here's a replacement patch to convert hwspinlock to use an > XArray instead of a radix tree. Compile tested only.
Okay, seems to work so far. Thank you again! Will merge your patch into my series with your credits. Now I just need to wrap XArray into struct seq_operations. Seems no one has needed that in the kernel so far. Some comments and questions to get a better understanding. > From 8ec88ed466e8153f546f7e8e69193cd5389488ee Mon Sep 17 00:00:00 2001 > From: "Matthew Wilcox (Oracle)" <[email protected]> > Date: Mon, 22 Jun 2026 09:38:30 -0400 > Subject: [PATCH] hwspinlock: Convert to XArray > > The radix tree is deprecated. The XArray uses the same data structure > with a nicer interface. The hwspinlock_tree_lock is not needed as the > spinlock built into the XArray is sufficient for all these cases. > > hwspin_lock_register_single() used to always return 0. Its caller > thinks it can return an errno, so I believe this to be a bug and so I > have restored its ability to return an error. I sent a patch for that previously and would rebase your patch on mine to keep the one patch per issue ration. > Signed-off-by: Matthew Wilcox (Oracle) <[email protected]> > --- > drivers/hwspinlock/hwspinlock_core.c | 133 ++++++++++----------------- > 1 file changed, 50 insertions(+), 83 deletions(-) > > diff --git a/drivers/hwspinlock/hwspinlock_core.c > b/drivers/hwspinlock/hwspinlock_core.c > index cc8e952a6772..1dd68b8410dd 100644 > --- a/drivers/hwspinlock/hwspinlock_core.c > +++ b/drivers/hwspinlock/hwspinlock_core.c > @@ -16,7 +16,7 @@ > #include <linux/types.h> > #include <linux/err.h> > #include <linux/jiffies.h> > -#include <linux/radix-tree.h> > +#include <linux/xarray.h> According to some quick grepping, there are 102 users of XArray including this header and 423 users which are not including this header. Do you think this is a useful improvement to add the header directly (per subsystem to keep the number of patches limited)? > - void **slot; Great, this obsoletes a fix concerning RCU annotations I have sent previously! > @@ -389,15 +375,9 @@ int of_hwspin_lock_get_id(struct device_node *np, int > index) > /* Find the hwspinlock device: we need its base_id */ > ret = -EPROBE_DEFER; > rcu_read_lock(); > - radix_tree_for_each_slot(slot, &hwspinlock_tree, &iter, 0) { > - hwlock = radix_tree_deref_slot(slot); > - if (unlikely(!hwlock)) > - continue; > - if (radix_tree_deref_retry(hwlock)) { > - slot = radix_tree_iter_retry(&iter); > + xas_for_each(&xas, hwlock, ULONG_MAX) { > + if (xas_retry(&xas, hwlock)) So, the unlikely(!hwlock) case cannot happen with XArray? > - ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED); > + ret = xas_get_mark(&xas, HWSPINLOCK_UNUSED); xas_get_mark() returns bool, so I will update the code to match that. Makes it more readable, too, IMO. The rest I could understand, I think. Looks much leaner, in deed. Will keep you in the loop once my next iteration is ready. Happy hacking, Wolfram
