Dynamic programming ops will modify the dt_host and there might be other function which are browsing the dt_host at the same time. To avoid the race conditions, adding rwlock for browsing the dt_host.
Signed-off-by: Vikram Garhwal <[email protected]> --- xen/common/device_tree.c | 27 +++++++++++++++++++++++++++ xen/include/xen/device_tree.h | 6 ++++++ 2 files changed, 33 insertions(+) diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c index acf26a411d..51ee2a5edf 100644 --- a/xen/common/device_tree.c +++ b/xen/common/device_tree.c @@ -140,6 +140,8 @@ const struct dt_property *dt_find_property(const struct dt_device_node *np, if ( !np ) return NULL; + read_lock(&dt_host->lock); + for ( pp = np->properties; pp; pp = pp->next ) { if ( dt_prop_cmp(pp->name, name) == 0 ) @@ -150,6 +152,7 @@ const struct dt_property *dt_find_property(const struct dt_device_node *np, } } + read_unlock(&dt_host->lock); return pp; } @@ -336,11 +339,14 @@ struct dt_device_node *dt_find_node_by_name(struct dt_device_node *from, struct dt_device_node *np; struct dt_device_node *dt; + read_lock(&dt_host->lock); + dt = from ? from->allnext : dt_host; dt_for_each_device_node(dt, np) if ( np->name && (dt_node_cmp(np->name, name) == 0) ) break; + read_unlock(&dt_host->lock); return np; } @@ -350,11 +356,14 @@ struct dt_device_node *dt_find_node_by_type(struct dt_device_node *from, struct dt_device_node *np; struct dt_device_node *dt; + read_lock(&dt_host->lock); + dt = from ? from->allnext : dt_host; dt_for_each_device_node(dt, np) if ( np->type && (dt_node_cmp(np->type, type) == 0) ) break; + read_unlock(&dt_host->lock); return np; } @@ -363,10 +372,13 @@ struct dt_device_node *device_tree_find_node_by_path(struct dt_device_node *dt, { struct dt_device_node *np; + read_lock(&dt_host->lock); + dt_for_each_device_node(dt, np) if ( np->full_name && (dt_node_cmp(np->full_name, path) == 0) ) break; + read_unlock(&dt_host->lock); return np; } @@ -450,6 +462,8 @@ dt_find_compatible_node(struct dt_device_node *from, struct dt_device_node *np; struct dt_device_node *dt; + read_lock(&dt_host->lock); + dt = from ? from->allnext : dt_host; dt_for_each_device_node(dt, np) { @@ -460,6 +474,7 @@ dt_find_compatible_node(struct dt_device_node *from, break; } + read_unlock(&dt_host->lock); return np; } @@ -470,13 +485,19 @@ dt_find_matching_node(struct dt_device_node *from, struct dt_device_node *np; struct dt_device_node *dt; + read_lock(&dt_host->lock); + dt = from ? from->allnext : dt_host; dt_for_each_device_node(dt, np) { if ( dt_match_node(matches, np) ) + { + read_unlock(&dt_host->lock); return np; + } } + read_unlock(&dt_host->lock); return NULL; } @@ -1052,10 +1073,13 @@ struct dt_device_node *dt_find_node_by_phandle(dt_phandle handle) { struct dt_device_node *np; + read_lock(&dt_host->lock); + dt_for_each_device_node(dt_host, np) if ( np->phandle == handle ) break; + read_unlock(&dt_host->lock); return np; } @@ -2102,6 +2126,9 @@ int unflatten_device_tree(const void *fdt, struct dt_device_node **mynodes) dt_dprintk(" <- unflatten_device_tree()\n"); + /* Init r/w lock for host device tree. */ + rwlock_init(&dt_host->lock); + return 0; } diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h index 51e251b0b4..bafc898f1c 100644 --- a/xen/include/xen/device_tree.h +++ b/xen/include/xen/device_tree.h @@ -18,6 +18,7 @@ #include <xen/string.h> #include <xen/types.h> #include <xen/list.h> +#include <xen/rwlock.h> #define DEVICE_TREE_MAX_DEPTH 16 @@ -106,6 +107,11 @@ struct dt_device_node { struct list_head domain_list; struct device dev; + + /* + * Lock that protects r/w updates to unflattened device tree i.e. dt_host. + */ + rwlock_t lock; }; #define dt_to_dev(dt_node) (&(dt_node)->dev) -- 2.17.1
