fix: tform: regression due to #797

The fix of #797 causes deadlocks when assigned MODMAX or MODMIN
dollars appear on their RHS, inside a function argument. In that
case, another lock on the dollar is attempted.

For example: `$dol = max_($dol,something);`

Use PTHREAD_MUTEX_RECURSIVE for dollar variables, such that a
thread may re-lock a dollar during assignment operations.

The MODSUM case has always deadlocked for such constructions.

Author: jodavies

check/fixes.frm

@@ -2476,6 +2476,48 @@ P;
 assert succeeded?
 assert result("F") =~ expr("9999")
 *--#] Issue268_2 :
+*--#[ Issue271 : 
+#-
+#define N "16"
+Symbol x,n;
+Local test = -{`N'*(`N'+1)/2} + <x^1>+...+<x^`N'>;
+.sort
+#$split = 0;
+Identify x^n?pos_ = n;
+$split = $split + term_;
+ModuleOption sum $split;
+.sort
+#message split = `$split'
+Print;
+.end
+assert succeeded?
+assert stdout =~ exact_pattern(<<EOF)
+~~~split = 0
+EOF
+assert result("test") =~ expr("0")
+*--#] Issue271 : 
+*--#[ Issue271b : 
+#-
+#define N "16"
+Symbol x,n;
+Local test = -{`N'*(`N'+1)/2} + <x^1>+...+<x^`N'>;
+.sort
+#$split = 0;
+$split = $split + term_;
+ModuleOption sum $split;
+.sort
+#message split = `$split'
+Print;
+.end
+# This symbolic sum doesn't work in TFORM, but does work in ParFORM:
+#pend_if threaded?
+assert succeeded?
+assert stdout =~ exact_pattern(<<EOF)
+~~~split = -136+x+x^2+x^3+x^4+x^5+x^6+x^7+x^8+x^9+x^10+x^11+x^12+x^13+x^14+x^15
++x^16
+EOF
+assert result("test") =~ expr("- 136 + x + x^2 + x^3 + x^4 + x^5 + x^6 + x^7 + x^8 + x^9 + x^10 + x^11 + x^12 + x^13 + x^14 + x^15 + x^16")
+*--#] Issue271b : 
 *--#[ Issue277 :
 * A question about addargs
 CFunction f,g,h;
@@ -4448,6 +4490,53 @@ assert warning?("Excess information in symmetric properties")
 assert warning?("Illegal information in number of arguments properties")
 assert warning?("Undefined $-variable")
 *--#] Issue766 : 
+*--#[ Issue796 : 
+* Regression: the fix for 796 deadlocks here:
+Symbol x;
+Local test = <x^1>+...+<x^128>;
+#$maxpow = 0;
+$maxpow = max_($maxpow,count_(x,1));
+ModuleOption maximum $maxpow;
+.sort
+#message maxpow: `$maxpow'
+.end
+assert succeeded?
+assert stdout =~ exact_pattern(<<'EOF')
+maxpow: 128
+EOF
+*--#] Issue796 : 
+*--#[ Issue796b : 
+* Regression: the fix for 796 deadlocks here:
+Symbol x;
+Local test = <x^1>+...+<x^128>;
+#$minpow = 129;
+$minpow = min_($minpow,count_(x,1));
+ModuleOption minimum $minpow;
+.sort
+#message minpow: `$minpow'
+.end
+assert succeeded?
+assert stdout =~ exact_pattern(<<'EOF')
+minpow: 1
+EOF
+*--#] Issue796b : 
+*--#[ Issue796c : 
+* This case has always deadlocked:
+Symbol x;
+Local test = <x^1>+...+<x^128>;
+#$sumpow = 129;
+$sumpow = max_($sumpow,count_(x,1));
+ModuleOption sum $sumpow;
+.sort
+#message sumpow: `$sumpow'
+.end
+# ParFORM does not pass this test
+#pend_if mpi?
+assert succeeded?
+assert stdout =~ exact_pattern(<<'EOF')
+sumpow: 129
+EOF
+*--#] Issue796c : 
 *--#[ PullReq535 :
 * This test requires more than the specified 50K workspace.
 #:maxtermsize 200

sources/checkpoint.c

@@ -2099,7 +2099,7 @@ int DoRecovery(int *moduletype)
 			R_COPY_B(d->where, size, void*);
 		}
 #ifdef WITHPTHREADS
-		d->pthreadslock = dummylock;
+		INIRECLOCK(d->pthreadslock);
 #endif
 		if ( d->nfactors > 1 ) {
 			R_COPY_B(d->factors,sizeof(FACDOLLAR)*d->nfactors,FACDOLLAR*);

sources/declare.h

@@ -462,6 +462,12 @@ static inline LONG ULongToLong(ULONG x)
 #define INILOCK(x)    pthread_mutex_t x = PTHREAD_MUTEX_INITIALIZER;
 #define EXTERNRWLOCK(x) extern pthread_rwlock_t x;
 #define INIRWLOCK(x)    pthread_rwlock_t x = PTHREAD_RWLOCK_INITIALIZER;
+#define INIRECLOCK(x) do { pthread_mutexattr_t attrib; \
+	pthread_mutexattr_init(&attrib); \
+	pthread_mutexattr_settype(&attrib, PTHREAD_MUTEX_RECURSIVE); \
+	pthread_mutex_init(&(x), &attrib); \
+	pthread_mutexattr_destroy(&attrib); \
+	} while(0)
 #ifdef DEBUGGINGLOCKS
 #include <asm/errno.h>
 #define LOCK(x)       while ( pthread_mutex_trylock(&(x)) == EBUSY ) {}

sources/dollar.c

@@ -35,8 +35,6 @@
 
 #include "form3.h"
 
-/* EXTERNLOCK(dummylock) */
-
 static UBYTE underscore[2] = {'_',0};
 
 /*
@@ -1566,7 +1564,7 @@ DOLLARS DolToTerms(PHEAD WORD numdollar)
 	newd->size = size;
 	newd->numdummies = d->numdummies;
 #ifdef WITHPTHREADS
-	newd->pthreadslock  = dummylock;
+	INIRECLOCK(newd->pthreadslock);
 #endif
 	size++;
 	NCOPY(t,w,size);

sources/module.c

@@ -718,7 +718,7 @@ UBYTE * DoModDollar(UBYTE *s, int type)
 							dlocal->where[i] = dglobal->where[i];
 						dlocal->where[dlocal->size] = 0;
 					}
-					dlocal->pthreadslock = dummylock;
+					INIRECLOCK(dlocal->pthreadslock);
 					dlocal->nfactors = dglobal->nfactors;
 					if ( dglobal->nfactors > 1 ) {
 						int nsize;

sources/names.c

@@ -2612,7 +2612,7 @@ int AddDollar(UBYTE *name, WORD type, WORD *start, LONG size)
 	dol->zero = 0;
 	dol->numdummies = 0;
 #ifdef WITHPTHREADS
-	dol->pthreadslock = dummylock;
+	INIRECLOCK(dol->pthreadslock);
 #endif
 	dol->nfactors = 0;
 	dol->factors = 0;