cfq-iosched: fix cfq_cic_link() race confition

[pandora-kernel.git] / block / cfq-iosched.c

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 3beed83..4c12869 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3184,7 +3184,7 @@ static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
                }
        }
 
-       if (ret)
+       if (ret && ret != -EEXIST)
                printk(KERN_ERR "cfq: cic link failed!\n");
 
        return ret;
@@ -3200,6 +3200,7 @@ cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
 {
        struct io_context *ioc = NULL;
        struct cfq_io_context *cic;
+       int ret;
 
        might_sleep_if(gfp_mask & __GFP_WAIT);
 
@@ -3207,6 +3208,7 @@ cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
        if (!ioc)
                return NULL;
 
+retry:
        cic = cfq_cic_lookup(cfqd, ioc);
        if (cic)
                goto out;
@@ -3215,7 +3217,12 @@ cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
        if (cic == NULL)
                goto err;
 
-       if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
+       ret = cfq_cic_link(cfqd, ioc, cic, gfp_mask);
+       if (ret == -EEXIST) {
+               /* someone has linked cic to ioc already */
+               cfq_cic_free(cic);
+               goto retry;
+       } else if (ret)
                goto err_free;
 
 out: