lightnvm: remove nested lock conflict with mm (5cd90785) · Commits · 戴 / test

If a media manager tries to initialize it targets upon media manager initialization, the media manager will need to know which target types are available in LightNVM. The lists of which managers and target types are available shares the same lock. Therefore, on initialization, the nvm_lock is taken by LightNVM core, which later leads to a deadlock when target types are enumerated by the media manager. Add an exclusive lock for target types to resolve this conflict. Signed-off-by:

Matias Bjørling <m@bjorling.me> Signed-off-by:

Jens Axboe <axboe@fb.com>

drivers/lightnvm/core.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -28,6 +28,7 @@
		#include <linux/sched/sysctl.h>

		static LIST_HEAD(nvm_tgt_types);
		static DECLARE_RWSEM(nvm_tgtt_lock);
		static LIST_HEAD(nvm_mgrs);
		static LIST_HEAD(nvm_devices);
		static DECLARE_RWSEM(nvm_lock);
		@@ -37,7 +38,7 @@ struct nvm_tgt_type nvm_find_target_type(const char name, int lock)
		struct nvm_tgt_type tmp, tt = NULL;

		if (lock)
		down_write(&nvm_lock);
		down_write(&nvm_tgtt_lock);

		list_for_each_entry(tmp, &nvm_tgt_types, list)
		if (!strcmp(name, tmp->name)) {
		@@ -46,7 +47,7 @@ struct nvm_tgt_type nvm_find_target_type(const char name, int lock)
		}

		if (lock)
		up_write(&nvm_lock);
		up_write(&nvm_tgtt_lock);
		return tt;
		}
		EXPORT_SYMBOL(nvm_find_target_type);
		@@ -55,12 +56,12 @@ int nvm_register_tgt_type(struct nvm_tgt_type *tt)
		{
		int ret = 0;

		down_write(&nvm_lock);
		down_write(&nvm_tgtt_lock);
		if (nvm_find_target_type(tt->name, 0))
		ret = -EEXIST;
		else
		list_add(&tt->list, &nvm_tgt_types);
		up_write(&nvm_lock);
		up_write(&nvm_tgtt_lock);

		return ret;
		}

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