Fix typo

Author: idoleat

concurrency-primer.tex

@@ -905,7 +905,7 @@ \subsection{ABA problem}
 
 In the example provided, the presence of ABA problem results in thread A being unaware that variable \monobox{v} has been altered.
 Since the comparison result indicates \monobox{v} unchanged, \monobox{v + 10} is swapped in.
-Here sleeping is only used to ensure the occurance of ABA problem.
+Here sleeping is only used to ensure the occurrence of ABA problem.
 In real world scenario, instead of sleeping, thread A could paused by being context switched for other tasks, including being preempted by higher priority tasks.
 This example seems harmless, but things can get nasty when atomic \textsc{RMW} operations are used in more complex data structures.
 
@@ -928,9 +928,9 @@ \subsection{ABA problem}
     \item Thread A is preempted.
     \item Thread B claims the job and successfully updates \monobox{thrd\_pool->head->prev}.
     \item Thread B sets thread pool state to idle.
-    \item Main thread fininshes waiting and adds more jobs.
+    \item Main thread finishes waiting and adds more jobs.
     \item Memory allocator reuses the recently freed memory as new jobs addresses.
-    \item Fortunately, the first added job has the same address as the one thread A holded.
+    \item Fortunately, the first added job has the same address as the one thread A held.
     \item Thread A is back in running state. The comparison result is equal so it updates \monobox{thrd\_pool->head->prev} with the old \monobox{job->prev}, which is already a dangling pointer.
     \item Another thread loads the dangling pointer from \monobox{thrd\_pool->head->prev}.
 \end{enumerate}
@@ -963,7 +963,7 @@ \subsection{ABA problem}
 \inputminted{c}{./examples/rmw_example_aba.c}
 
 Notice that, in the \monobox{struct idle\_job}, a union is used for type punning, which bundles the pointer and version number for compare-and-swap.
-Directly casting a job pointer to a pointer that points to a 16-byte object is undefined behavior (due to having different alignment), thus type punnined is used instead.
+Directly casting a job pointer to a pointer that points to a 16-byte object is undefined behavior (due to having different alignment), thus type punning is used instead.
 By using this techniques, \monobox{struct idle\_job} still can be accessed normally in other places, minimizing code modification.
 Compiler optimizations are conservative on type punning, but it is acceptable for atomic operations.
 See \secref{fusing}.