From 21718bbbfa2a4bf4992bd295e25cbc67868dcfc1 Mon Sep 17 00:00:00 2001 From: Attila Kovacs Date: Wed, 20 Jul 2022 17:03:28 -0400 Subject: Eliminate deadlocks in connects with an MT environment In cnlt_dg_freeres() and clnt_vc_freeres(), cond_signal() is called after unlocking the mutex (clnt_fd_lock). The manual of pthread_cond_signal() allows that, but mentions that for consistent scheduling, cond_signal() should be called with the waiting mutex locked. clnt_fd_lock is locked on L171, but then not released if jumping to the err1 label on an error (L175 and L180). This means that those errors will deadlock all further operations that require clnt_fd_lock access. Same in clnt_vc.c in clnt_vc_create, on lines 215, 222, and 230 respectively. Signed-off-by: Steve Dickson --- src/clnt_dg.c | 9 ++++++--- src/clnt_vc.c | 12 ++++++++---- 2 files changed, 14 insertions(+), 7 deletions(-) (limited to 'src') diff --git a/src/clnt_dg.c b/src/clnt_dg.c index b3d82e7..7c5d22e 100644 --- a/src/clnt_dg.c +++ b/src/clnt_dg.c @@ -101,9 +101,9 @@ extern mutex_t clnt_fd_lock; #define release_fd_lock(fd_lock, mask) { \ mutex_lock(&clnt_fd_lock); \ fd_lock->active = FALSE; \ - mutex_unlock(&clnt_fd_lock); \ thr_sigsetmask(SIG_SETMASK, &(mask), NULL); \ cond_signal(&fd_lock->cv); \ + mutex_unlock(&clnt_fd_lock); \ } static const char mem_err_clnt_dg[] = "clnt_dg_create: out of memory"; @@ -172,12 +172,15 @@ clnt_dg_create(fd, svcaddr, program, version, sendsz, recvsz) if (dg_fd_locks == (fd_locks_t *) NULL) { dg_fd_locks = fd_locks_init(); if (dg_fd_locks == (fd_locks_t *) NULL) { + mutex_unlock(&clnt_fd_lock); goto err1; } } fd_lock = fd_lock_create(fd, dg_fd_locks); - if (fd_lock == (fd_lock_t *) NULL) + if (fd_lock == (fd_lock_t *) NULL) { + mutex_unlock(&clnt_fd_lock); goto err1; + } mutex_unlock(&clnt_fd_lock); thr_sigsetmask(SIG_SETMASK, &(mask), NULL); @@ -573,9 +576,9 @@ clnt_dg_freeres(cl, xdr_res, res_ptr) cu->cu_fd_lock->active = TRUE; xdrs->x_op = XDR_FREE; dummy = (*xdr_res)(xdrs, res_ptr); - mutex_unlock(&clnt_fd_lock); thr_sigsetmask(SIG_SETMASK, &mask, NULL); cond_signal(&cu->cu_fd_lock->cv); + mutex_unlock(&clnt_fd_lock); return (dummy); } diff --git a/src/clnt_vc.c b/src/clnt_vc.c index a07e297..3c73e65 100644 --- a/src/clnt_vc.c +++ b/src/clnt_vc.c @@ -153,9 +153,9 @@ extern mutex_t clnt_fd_lock; #define release_fd_lock(fd_lock, mask) { \ mutex_lock(&clnt_fd_lock); \ fd_lock->active = FALSE; \ - mutex_unlock(&clnt_fd_lock); \ thr_sigsetmask(SIG_SETMASK, &(mask), (sigset_t *) NULL); \ cond_signal(&fd_lock->cv); \ + mutex_unlock(&clnt_fd_lock); \ } static const char clnt_vc_errstr[] = "%s : %s"; @@ -216,7 +216,9 @@ clnt_vc_create(fd, raddr, prog, vers, sendsz, recvsz) if (vc_fd_locks == (fd_locks_t *) NULL) { vc_fd_locks = fd_locks_init(); if (vc_fd_locks == (fd_locks_t *) NULL) { - struct rpc_createerr *ce = &get_rpc_createerr(); + struct rpc_createerr *ce; + mutex_unlock(&clnt_fd_lock); + ce = &get_rpc_createerr(); ce->cf_stat = RPC_SYSTEMERROR; ce->cf_error.re_errno = errno; goto err; @@ -224,7 +226,9 @@ clnt_vc_create(fd, raddr, prog, vers, sendsz, recvsz) } fd_lock = fd_lock_create(fd, vc_fd_locks); if (fd_lock == (fd_lock_t *) NULL) { - struct rpc_createerr *ce = &get_rpc_createerr(); + struct rpc_createerr *ce; + mutex_unlock(&clnt_fd_lock); + ce = &get_rpc_createerr(); ce->cf_stat = RPC_SYSTEMERROR; ce->cf_error.re_errno = errno; goto err; @@ -495,9 +499,9 @@ clnt_vc_freeres(cl, xdr_res, res_ptr) cond_wait(&ct->ct_fd_lock->cv, &clnt_fd_lock); xdrs->x_op = XDR_FREE; dummy = (*xdr_res)(xdrs, res_ptr); - mutex_unlock(&clnt_fd_lock); thr_sigsetmask(SIG_SETMASK, &(mask), NULL); cond_signal(&ct->ct_fd_lock->cv); + mutex_unlock(&clnt_fd_lock); return dummy; } -- cgit v1.2.1