From: Sebastian Andrzej Siewior Date: Fri, 31 Aug 2018 14:16:30 +0200 Subject: [PATCH] of: allocate / free phandle cache outside of the devtree_lock Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.18/older/patches-4.18.7-rt5.tar.xz The phandle cache code allocates memory while holding devtree_lock which is a raw_spinlock_t. Memory allocation (and free()) is not possible on RT while a raw_spinlock_t is held. Invoke the kfree() and kcalloc() while the lock is dropped. Cc: Rob Herring Cc: Frank Rowand Cc: devicetree@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior --- drivers/of/base.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -108,46 +108,52 @@ void of_populate_phandle_cache(void) u32 cache_entries; struct device_node *np; u32 phandles = 0; + struct device_node **shadow; raw_spin_lock_irqsave(&devtree_lock, flags); - - kfree(phandle_cache); + shadow = phandle_cache; phandle_cache = NULL; for_each_of_allnodes(np) if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL) phandles++; + raw_spin_unlock_irqrestore(&devtree_lock, flags); + if (!phandles) goto out; cache_entries = roundup_pow_of_two(phandles); phandle_cache_mask = cache_entries - 1; - phandle_cache = kcalloc(cache_entries, sizeof(*phandle_cache), - GFP_ATOMIC); - if (!phandle_cache) - goto out; + kfree(shadow); + shadow = kcalloc(cache_entries, sizeof(*phandle_cache), GFP_KERNEL); + + if (!shadow) + return; + raw_spin_lock_irqsave(&devtree_lock, flags); + phandle_cache = shadow; for_each_of_allnodes(np) if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL) phandle_cache[np->phandle & phandle_cache_mask] = np; -out: raw_spin_unlock_irqrestore(&devtree_lock, flags); } int of_free_phandle_cache(void) { unsigned long flags; + struct device_node **shadow; raw_spin_lock_irqsave(&devtree_lock, flags); - kfree(phandle_cache); + shadow = phandle_cache; phandle_cache = NULL; raw_spin_unlock_irqrestore(&devtree_lock, flags); + kfree(shadow); return 0; } #if !defined(CONFIG_MODULES)