Eric Lee / linux-smarc-t335x-v3.2

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Commit 3168b0780d06ace875696f8a648d04d6089654e5

Authored by Satyam Sharma
Committed by Steven Whitehouse
1 parent b524fe646c
Exists in master and in 4 other branches v3.2_AM335xPSP_04.06.00.11, v3.2_NEWT335xPSP_04.06.00.11, v3.2_SBC_SMARTMEN, v3.2_SMARCT335xPSP_04.06.00.11

[DLM] fix a couple of races 

Fix two races in fs/dlm/config.c:

(1) Grab the configfs subsystem semaphore before calling
config_group_find_obj() in get_space(). This solves a potential race
between get_space() and concurrent mkdir(2) or rmdir(2).

(2) Grab a reference on the found config_item _while_ holding the configfs
subsystem semaphore in get_comm(), and not after it. This solves a
potential race between get_comm() and concurrent rmdir(2).

Signed-off-by: Satyam Sharma <ssatyam@cse.iitk.ac.in>
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

Showing 1 changed file with 11 additions and 4 deletions Side-by-side Diff

... ... @@ -748,9 +748,16 @@
748 748  
749 749 static struct space *get_space(char *name)
750 750 {
  751 + struct config_item *i;
  752 +
751 753 if (!space_list)
752 754 return NULL;
753   - return to_space(config_group_find_obj(space_list, name));
  755 +
  756 + down(&space_list->cg_subsys->su_sem);
  757 + i = config_group_find_obj(space_list, name);
  758 + up(&space_list->cg_subsys->su_sem);
  759 +
  760 + return to_space(i);
754 761 }
755 762  
756 763 static void put_space(struct space *sp)
757 764  
758 765  
... ... @@ -776,20 +783,20 @@
776 783 if (cm->nodeid != nodeid)
777 784 continue;
778 785 found = 1;
  786 + config_item_get(i);
779 787 break;
780 788 } else {
781 789 if (!cm->addr_count ||
782 790 memcmp(cm->addr[0], addr, sizeof(*addr)))
783 791 continue;
784 792 found = 1;
  793 + config_item_get(i);
785 794 break;
786 795 }
787 796 }
788 797 up(&clusters_root.subsys.su_sem);
789 798  
790   - if (found)
791   - config_item_get(i);
792   - else
  799 + if (!found)
793 800 cm = NULL;
794 801 return cm;
795 802 }