sharpetronics/PostgreSQL
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-10 00:01:28 -04:00
Code Issues Projects Releases Wiki Activity

Fix logic bug in dsm_attach().

Browse Source 
The previous coding would potentially cause attaching to segment A to
fail if segment B was at the same time in the process of going away.

Andres Freund, with a comment tweak by me
This commit is contained in:
Robert Haas 2014-05-06 13:37:46 -04:00
parent 4335c95815
commit e0124230ba
1 changed files with 8 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
src/backend/storage/ipc/dsm.c
View File

@ -566,6 +566,10 @@ dsm_attach(dsm_handle h)
if (dsm_control->item[i].refcnt == 0) if (dsm_control->item[i].refcnt == 0)
continue; continue;
/* If the handle doesn't match, it's not the slot we want. */
if (dsm_control->item[i].handle != seg->handle)
continue;
/* /*
* If the reference count is 1, the slot is still in use, but the * If the reference count is 1, the slot is still in use, but the
* segment is in the process of going away. Treat that as if we * segment is in the process of going away. Treat that as if we
@ -574,14 +578,11 @@ dsm_attach(dsm_handle h)
if (dsm_control->item[i].refcnt == 1) if (dsm_control->item[i].refcnt == 1)
break; break;
/* Otherwise, if the descriptor matches, we've found a match. */ /* Otherwise we've found a match. */
if (dsm_control->item[i].handle == seg->handle)
{
dsm_control->item[i].refcnt++; dsm_control->item[i].refcnt++;
seg->control_slot = i; seg->control_slot = i;
break; break;
} }
}
LWLockRelease(DynamicSharedMemoryControlLock); LWLockRelease(DynamicSharedMemoryControlLock);
/* /*