debugging: slides: mention tasklets deprecation and BH workqueues

Tasklets are being slowly removed from the kernel, so it does not make
sense anymore to mention it as the default solution to run code in softirq.
Commit 4cb1ef64609f ("workqueue: Implement BH workqueues to eventually
replace tasklets") in upstream kernel has introduced the BH workqueue, and
many commits follow to convert tasklets already present in the kernel to
BH workqueues.

See also https://lwn.net/Articles/960041/ for details about why BH
workqueues are being introduced.

Signed-off-by: Alexis Lothoré <[email protected]>

slides/debugging-linux-application-stack/debugging-linux-application-stack.tex

@@ -426,8 +426,10 @@ \subsection{Kernel execution contexts}
       \item Same context as executing interrupt handler so sleeping is not
             allowed.
     \end{itemize}
-    \item Tasklets are using softirqs to execute their work so they run in the
-          same context and the same constraints are applied.
+    \item Anyone wanting to run some code in softirq context should likely not
+    create its own but prefer some entities implemented on top of it. There are
+    for example tasklets, and the BH workqueues (Bottom Half workqueues) which
+    aim to replace tasklets since 6.9.
   \end{itemize}
 \end{frame}