util/nvmutil: limit EAGAIN/EINTR retries

set it really high though, so it's still
basically reliably

an EINTR/EAGAIN storm could cause problems
in prw()

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/nvmutil/nvmutil.c

@@ -2261,6 +2261,12 @@ prw(int fd, void *mem, unsigned long nrw,
     int loop_eagain, int loop_eintr,
     int off_reset)
 {
+#ifndef MAX_EAGAIN_RETRIES
+	unsigned long retries = 100000;
+#else
+	unsigned long retries = MAX_EAGAIN_RETRIES;
+#endif
+
 	long r;
 	int positional_rw;
 	struct stat st;
@@ -2388,8 +2394,9 @@ real_pread_pwrite:
 			}
 
 		} while (r == -1 &&
-		    (errno == try_err(loop_eintr, EINTR)
+		    (errno == try_err(loop_eintr, EINTR) ||
-		    || errno == try_err(loop_eagain, EAGAIN)));
+		     errno == try_err(loop_eagain, EAGAIN)) &&
+		    retries++ < MAX_EAGAIN_RETRIES);
 	}
 
 	saved_errno = errno;

util/nvmutil/nvmutil.h

@@ -36,6 +36,10 @@ int fchmod(int fd, mode_t mode);
 #define HAVE_REAL_PREAD_PWRITE 0
 #endif
 
+#ifndef MAX_EAGAIN_RETRIES
+#define MAX_EAGAIN_RETRIES 100000
+#endif
+
 #ifndef LOOP_EAGAIN
 #define LOOP_EAGAIN 1
 #endif