svn commit: r360962 - stable/12/sys/kern

[Mark Johnston]

Author: markj
Date: Tue May 12 14:01:14 2020
New Revision: 360962
URL: https://svnweb.freebsd.org/changeset/base/360962

Log:
  MFC r360438:
  Make sendfile(SF_SYNC)'s CV wait interruptible.

Modified:
  stable/12/sys/kern/kern_sendfile.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/kern/kern_sendfile.c
==============================================================================
--- stable/12/sys/kern/kern_sendfile.c  Tue May 12 14:01:12 2020        
(r360961)
+++ stable/12/sys/kern/kern_sendfile.c  Tue May 12 14:01:14 2020        
(r360962)
@@ -95,8 +95,36 @@ struct sendfile_sync {
        struct mtx      mtx;
        struct cv       cv;
        unsigned        count;
+       bool            waiting;
 };
 
+static void
+sendfile_sync_destroy(struct sendfile_sync *sfs)
+{
+       KASSERT(sfs->count == 0, ("sendfile sync %p still busy", sfs));
+
+       cv_destroy(&sfs->cv);
+       mtx_destroy(&sfs->mtx);
+       free(sfs, M_SENDFILE);
+}
+
+static void
+sendfile_sync_signal(struct sendfile_sync *sfs)
+{
+       mtx_lock(&sfs->mtx);
+       KASSERT(sfs->count > 0, ("sendfile sync %p not busy", sfs));
+       if (--sfs->count == 0) {
+               if (!sfs->waiting) {
+                       /* The sendfile() waiter was interrupted by a signal. */
+                       sendfile_sync_destroy(sfs);
+                       return;
+               } else {
+                       cv_signal(&sfs->cv);
+               }
+       }
+       mtx_unlock(&sfs->mtx);
+}
+
 counter_u64_t sfstat[sizeof(struct sfstat) / sizeof(uint64_t)];
 
 static void
@@ -140,12 +168,7 @@ sendfile_free_mext(struct mbuf *m)
 
        if (m->m_ext.ext_flags & EXT_FLAG_SYNC) {
                struct sendfile_sync *sfs = m->m_ext.ext_arg2;
-
-               mtx_lock(&sfs->mtx);
-               KASSERT(sfs->count > 0, ("Sendfile sync botchup count == 0"));
-               if (--sfs->count == 0)
-                       cv_signal(&sfs->cv);
-               mtx_unlock(&sfs->mtx);
+               sendfile_sync_signal(sfs);
        }
 }
 
@@ -535,6 +558,7 @@ vn_sendfile(struct file *fp, int sockfd, struct uio *h
                sfs = malloc(sizeof(*sfs), M_SENDFILE, M_WAITOK | M_ZERO);
                mtx_init(&sfs->mtx, "sendfile", NULL, MTX_DEF);
                cv_init(&sfs->cv, "sendfile");
+               sfs->waiting = true;
        }
 
        rem = nbytes ? omin(nbytes, obj_size - offset) : obj_size - offset;
@@ -896,11 +920,13 @@ out:
        if (sfs != NULL) {
                mtx_lock(&sfs->mtx);
                if (sfs->count != 0)
-                       cv_wait(&sfs->cv, &sfs->mtx);
-               KASSERT(sfs->count == 0, ("sendfile sync still busy"));
-               cv_destroy(&sfs->cv);
-               mtx_destroy(&sfs->mtx);
-               free(sfs, M_SENDFILE);
+                       error = cv_wait_sig(&sfs->cv, &sfs->mtx);
+               if (sfs->count == 0) {
+                       sendfile_sync_destroy(sfs);
+               } else {
+                       sfs->waiting = false;
+                       mtx_unlock(&sfs->mtx);
+               }
        }
 
        if (error == ERESTART)
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