FMC: fix locking in sample chardev driver (783c2fb1) · Commits · 戴 / test

The fmc-chardev module was over-locking, by calling misc register/unregister while holding its spinlock. This reported a "scheduling while atomic" error. Since the misc driver already serializes operations internally, this commit downgrades the fmc-chardev lock to just cover its own list. Reported-by:

Sasha Levin <sasha.levin@oracle.com> Reported-by:

Fengguang Wu <fengguang.wu@intel.com> Signed-off-by:

Alessandro Rubini <rubini@gnudd.com> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/fmc/fmc-chardev.c

+4 −5

Original line number	Diff line number	Diff line
		@@ -143,18 +143,17 @@ static int fc_probe(struct fmc_device *fmc)
		fc->misc.fops = &fc_fops;
		fc->misc.name = kstrdup(dev_name(&fmc->dev), GFP_KERNEL);

		spin_lock(&fc_lock);
		ret = misc_register(&fc->misc);
		if (ret < 0)
		goto err_unlock;
		goto out;
		spin_lock(&fc_lock);
		list_add(&fc->list, &fc_devices);
		spin_unlock(&fc_lock);
		dev_info(&fc->fmc->dev, "Created misc device \"%s\"\n",
		fc->misc.name);
		return 0;

		err_unlock:
		spin_unlock(&fc_lock);
		out:
		kfree(fc->misc.name);
		kfree(fc);
		return ret;
		@@ -174,10 +173,10 @@ static int fc_remove(struct fmc_device *fmc)

		spin_lock(&fc_lock);
		list_del(&fc->list);
		spin_unlock(&fc_lock);
		misc_deregister(&fc->misc);
		kfree(fc->misc.name);
		kfree(fc);
		spin_unlock(&fc_lock);

		return 0;
		}

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