Refactor the async wait fd logic

Implementation experience has shown that the original plan for async wait
fds was too simplistic. Originally the async logic created a pipe internally
and user/engine code could then get access to it via API calls. It is more
flexible if the engine is able to create its own fd and provide it to the
async code.

Another issue is that there can be a lot of churn in the fd value within
the context of (say) a single SSL connection leading to continually adding
and removing fds from (say) epoll. It is better if we can provide some
stability of the fd value across a whole SSL connection. This is
problematic because an engine has no concept of an SSL connection.

This commit refactors things to introduce an ASYNC_WAIT_CTX which acts as a
proxy for an SSL connection down at the engine layer.

Reviewed-by: Richard Levitte <levitte@openssl.org>

1 files changed, 9 insertions, 39 deletions

diff --git a/crypto/async/async.c b/crypto/async/async.c
index ebc5ebbe93..de2ec4a7c6 100644
--- a/crypto/async/async.c
+++ b/crypto/async/async.c
@@ -119,26 +119,14 @@ static int async_ctx_free(void)
 static ASYNC_JOB *async_job_new(void)
 {
     ASYNC_JOB *job = NULL;
-    OSSL_ASYNC_FD pipefds[2];
 
-    job = OPENSSL_malloc(sizeof (ASYNC_JOB));
+    job = OPENSSL_zalloc(sizeof (ASYNC_JOB));
     if (job == NULL) {
         ASYNCerr(ASYNC_F_ASYNC_JOB_NEW, ERR_R_MALLOC_FAILURE);
         return NULL;
     }
 
-    if (!async_pipe(pipefds)) {
-        OPENSSL_free(job);
-        ASYNCerr(ASYNC_F_ASYNC_JOB_NEW, ASYNC_R_CANNOT_CREATE_WAIT_PIPE);
-        return NULL;
-    }
-
-    job->wake_set = 0;
-    job->wait_fd = pipefds[0];
-    job->wake_fd = pipefds[1];
-
     job->status = ASYNC_JOB_RUNNING;
-    job->funcargs = NULL;
 
     return job;
 }
@@ -148,8 +136,6 @@ static void async_job_free(ASYNC_JOB *job)
     if (job != NULL) {
         OPENSSL_free(job->funcargs);
         async_fibre_free(&job->fibrectx);
-        async_close_fd(job->wait_fd);
-        async_close_fd(job->wake_fd);
         OPENSSL_free(job);
     }
 }
@@ -219,8 +205,8 @@ void async_start_func(void)
     }
 }
 
-int ASYNC_start_job(ASYNC_JOB **job, int *ret, int (*func)(void *),
-                         void *args, size_t size)
+int ASYNC_start_job(ASYNC_JOB **job, ASYNC_WAIT_CTX *wctx, int *ret,
+                    int (*func)(void *), void *args, size_t size)
 {
     async_ctx *ctx = async_get_ctx();
     if (ctx == NULL)
@@ -237,6 +223,7 @@ int ASYNC_start_job(ASYNC_JOB **job, int *ret, int (*func)(void *),
         if (ctx->currjob != NULL) {
             if (ctx->currjob->status == ASYNC_JOB_STOPPING) {
                 *ret = ctx->currjob->ret;
+                ctx->currjob->waitctx = NULL;
                 async_release_job(ctx->currjob);
                 ctx->currjob = NULL;
                 *job = NULL;
@@ -289,6 +276,7 @@ int ASYNC_start_job(ASYNC_JOB **job, int *ret, int (*func)(void *),
         }
 
         ctx->currjob->func = func;
+        ctx->currjob->waitctx = wctx;
         if (!async_fibre_swapcontext(&ctx->dispatcher,
                 &ctx->currjob->fibrectx, 1)) {
             ASYNCerr(ASYNC_F_ASYNC_START_JOB, ASYNC_R_FAILED_TO_SWAP_CONTEXT);
@@ -303,7 +291,6 @@ err:
     return ASYNC_ERR;
 }
 
-
 int ASYNC_pause_job(void)
 {
     ASYNC_JOB *job;
@@ -327,6 +314,8 @@ int ASYNC_pause_job(void)
         ASYNCerr(ASYNC_F_ASYNC_PAUSE_JOB, ASYNC_R_FAILED_TO_SWAP_CONTEXT);
         return 0;
     }
+    /* Reset counts of added and deleted fds */
+    async_wait_ctx_reset_counts(job->waitctx);
 
     return 1;
 }
@@ -441,28 +430,9 @@ ASYNC_JOB *ASYNC_get_current_job(void)
     return ctx->currjob;
 }
 
-OSSL_ASYNC_FD ASYNC_get_wait_fd(ASYNC_JOB *job)
-{
-    return job->wait_fd;
-}
-
-void ASYNC_wake(ASYNC_JOB *job)
-{
-    char dummy = 0;
-
-    if (job->wake_set)
-        return;
-    async_write1(job->wake_fd, &dummy);
-    job->wake_set = 1;
-}
-
-void ASYNC_clear_wake(ASYNC_JOB *job)
+ASYNC_WAIT_CTX *ASYNC_get_wait_ctx(ASYNC_JOB *job)
 {
-    char dummy = 0;
-    if (!job->wake_set)
-        return;
-    async_read1(job->wait_fd, &dummy);
-    job->wake_set = 0;
+    return job->waitctx;
 }
 
 void ASYNC_block_pause(void)