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FMC: fix locking in sample chardev driver

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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>
This commit is contained in:
Alessandro Rubini 2013-07-16 12:58:01 +02:00 committed by Greg Kroah-Hartman
parent 5f90b9b484
commit 783c2fb1b8
1 changed files with 4 additions and 5 deletions
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9
drivers/fmc/fmc-chardev.c
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@ -143,18 +143,17 @@ static int fc_probe(struct fmc_device *fmc)
fc->misc.fops = &fc_fops; fc->misc.fops = &fc_fops;
fc->misc.name = kstrdup(dev_name(&fmc->dev), GFP_KERNEL); fc->misc.name = kstrdup(dev_name(&fmc->dev), GFP_KERNEL);
spin_lock(&fc_lock);
ret = misc_register(&fc->misc); ret = misc_register(&fc->misc);
if (ret < 0) if (ret < 0)
goto err_unlock; goto out;
spin_lock(&fc_lock);
list_add(&fc->list, &fc_devices); list_add(&fc->list, &fc_devices);
spin_unlock(&fc_lock); spin_unlock(&fc_lock);
dev_info(&fc->fmc->dev, "Created misc device \"%s\"\n", dev_info(&fc->fmc->dev, "Created misc device \"%s\"\n",
fc->misc.name); fc->misc.name);
return 0; return 0;
err_unlock: out:
spin_unlock(&fc_lock);
kfree(fc->misc.name); kfree(fc->misc.name);
kfree(fc); kfree(fc);
return ret; return ret;
@ -174,10 +173,10 @@ static int fc_remove(struct fmc_device *fmc)
spin_lock(&fc_lock); spin_lock(&fc_lock);
list_del(&fc->list); list_del(&fc->list);
spin_unlock(&fc_lock);
misc_deregister(&fc->misc); misc_deregister(&fc->misc);
kfree(fc->misc.name); kfree(fc->misc.name);
kfree(fc); kfree(fc);
spin_unlock(&fc_lock);
return 0; return 0;
} }