mirror/labs-bird
1
0
Fork 0
mirror of https://gitlab.labs.nic.cz/labs/bird.git synced 2024-05-11 16:54:54 +00:00
Code Releases Activity

Fixed a bug in hot page global storage

Browse Source 
The original algorithm was suffering from an ABA race condition:

A: fp = page_stack
B: completely allocates the same page and writes into it some data
A: unsuspecting, loads (invalid) next = fp->next
B: finishes working with the page and returns it back to page_stack
A: compare-exchange page_stack: fp => next succeeds and writes garbage
to page_stack

Fixed this by using an implicit spinlock in hot page allocator.
This commit is contained in:
Maria Matejka
2023-05-05 09:39:13 +02:00
parent 00f30ac40b
commit a95141111c
5 changed files with 128 additions and 37 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
lib/birdlib.h
View File

@@ -183,7 +183,11 @@ void bug(const char *msg, ...) NORET;
void debug(const char *msg, ...); /* Printf to debug output */
void debug_safe(const char *msg); /* Printf to debug output, async-safe */
/* Internal thread ID, useful for logging */
extern _Atomic uint max_thread_id;
extern _Thread_local uint this_thread_id;
#define THIS_THREAD_ID (this_thread_id ?: (this_thread_id = atomic_fetch_add_explicit(&max_thread_id, 1, memory_order_acq_rel)))
/* Debugging */