cd(4) M_WAITOK allocations with periph lock held

[Scott Long]

How about the attached match instead.  It refactors the code so that 
unlocks aren't needed.

Scott

On Tue, 1 Dec 2009, Jaakko Heinonen wrote:

>
> Hi,
>
> There are some M_WAITOK malloc invocations with periph lock held in
> cd(4). Below is a link to a patch which drops the periph lock while
> doing those allocations. Comments/review?
>
> ---
>
> Drop periph lock while allocating memory with M_WAITOK flag in
> cdreportkey(), cdsendkey() and cdreaddvdstructure().
>
> PR:		kern/130735
> Tested by:	Eygene Ryabinkin
>
> The patch against head:
>
> http://people.freebsd.org/~jh/patches/scsi_cd-M_WAITOK-fixes.diff
>
> -- 
> Jaakko
> _______________________________________________
> freebsd-scsi at freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-scsi
> To unsubscribe, send any mail to "freebsd-scsi-unsubscribe at freebsd.org"
>
-------------- next part --------------
Index: scsi_cd.c
===================================================================
RCS file: /usr1/ncvs/src/sys/cam/scsi/scsi_cd.c,v
retrieving revision 1.112
diff -u -r1.112 scsi_cd.c
--- scsi_cd.c	14 Nov 2009 20:13:38 -0000	1.112
+++ scsi_cd.c	1 Dec 2009 21:28:00 -0000
@@ -2673,12 +2673,10 @@
 
 		authinfo = (struct dvd_authinfo *)addr;
 
-		cam_periph_lock(periph);
 		if (cmd == DVDIOCREPORTKEY)
 			error = cdreportkey(periph, authinfo);
 		else
 			error = cdsendkey(periph, authinfo);
-		cam_periph_unlock(periph);
 		break;
 		}
 	case DVDIOCREADSTRUCTURE: {
@@ -2686,9 +2684,7 @@
 
 		dvdstruct = (struct dvd_struct *)addr;
 
-		cam_periph_lock(periph);
 		error = cdreaddvdstructure(periph, dvdstruct);
-		cam_periph_unlock(periph);
 
 		break;
 	}
@@ -3732,8 +3728,6 @@
 	databuf = NULL;
 	lba = 0;
 
-	ccb = cdgetccb(periph, CAM_PRIORITY_NORMAL);
-
 	switch (authinfo->format) {
 	case DVD_REPORT_AGID:
 		length = sizeof(struct scsi_report_key_data_agid);
@@ -3759,9 +3753,7 @@
 		length = 0;
 		break;
 	default:
-		error = EINVAL;
-		goto bailout;
-		break; /* NOTREACHED */
+		return (EINVAL);
 	}
 
 	if (length != 0) {
@@ -3769,6 +3761,8 @@
 	} else
 		databuf = NULL;
 
+	cam_periph_lock(periph);
+	ccb = cdgetccb(periph, CAM_PRIORITY_NORMAL);
 
 	scsi_report_key(&ccb->csio,
 			/* retries */ 1,
@@ -3870,11 +3864,12 @@
 		break; /* NOTREACHED */
 	}
 bailout:
+	xpt_release_ccb(ccb);
+	cam_periph_unlock(periph);
+
 	if (databuf != NULL)
 		free(databuf, M_DEVBUF);
 
-	xpt_release_ccb(ccb);
-
 	return(error);
 }
 
@@ -3889,8 +3884,6 @@
 	error = 0;
 	databuf = NULL;
 
-	ccb = cdgetccb(periph, CAM_PRIORITY_NORMAL);
-
 	switch(authinfo->format) {
 	case DVD_SEND_CHALLENGE: {
 		struct scsi_report_key_data_challenge *challenge_data;
@@ -3942,11 +3935,12 @@
 		break;
 	}
 	default:
-		error = EINVAL;
-		goto bailout;
-		break; /* NOTREACHED */
+		return (EINVAL);
 	}
 
+	cam_periph_lock(periph);
+	ccb = cdgetccb(periph, CAM_PRIORITY_NORMAL);
+
 	scsi_send_key(&ccb->csio,
 		      /* retries */ 1,
 		      /* cbfcnp */ cddone,
@@ -3963,11 +3957,12 @@
 
 bailout:
 
+	xpt_release_ccb(ccb);
+	cam_periph_unlock(periph);
+
 	if (databuf != NULL)
 		free(databuf, M_DEVBUF);
 
-	xpt_release_ccb(ccb);
-
 	return(error);
 }
 
@@ -3985,8 +3980,6 @@
 	/* The address is reserved for many of the formats */
 	address = 0;
 
-	ccb = cdgetccb(periph, CAM_PRIORITY_NORMAL);
-
 	switch(dvdstruct->format) {
 	case DVD_STRUCT_PHYSICAL:
 		length = sizeof(struct scsi_read_dvd_struct_data_physical);
@@ -4004,13 +3997,7 @@
 		length = sizeof(struct scsi_read_dvd_struct_data_manufacturer);
 		break;
 	case DVD_STRUCT_CMI:
-		error = ENODEV;
-		goto bailout;
-#ifdef notyet
-		length = sizeof(struct scsi_read_dvd_struct_data_copy_manage);
-		address = dvdstruct->address;
-#endif
-		break; /* NOTREACHED */
+		return (ENODEV);
 	case DVD_STRUCT_PROTDISCID:
 		length = sizeof(struct scsi_read_dvd_struct_data_prot_discid);
 		break;
@@ -4027,21 +4014,9 @@
 		length = sizeof(struct scsi_read_dvd_struct_data_spare_area);
 		break;
 	case DVD_STRUCT_RMD_LAST:
-		error = ENODEV;
-		goto bailout;
-#ifdef notyet
-		length = sizeof(struct scsi_read_dvd_struct_data_rmd_borderout);
-		address = dvdstruct->address;
-#endif
-		break; /* NOTREACHED */
+		return (ENODEV);
 	case DVD_STRUCT_RMD_RMA:
-		error = ENODEV;
-		goto bailout;
-#ifdef notyet
-		length = sizeof(struct scsi_read_dvd_struct_data_rmd);
-		address = dvdstruct->address;
-#endif
-		break; /* NOTREACHED */
+		return (ENODEV);
 	case DVD_STRUCT_PRERECORDED:
 		length = sizeof(struct scsi_read_dvd_struct_data_leadin);
 		break;
@@ -4049,13 +4024,7 @@
 		length = sizeof(struct scsi_read_dvd_struct_data_disc_id);
 		break;
 	case DVD_STRUCT_DCB:
-		error = ENODEV;
-		goto bailout;
-#ifdef notyet
-		length = sizeof(struct scsi_read_dvd_struct_data_dcb);
-		address = dvdstruct->address;
-#endif
-		break; /* NOTREACHED */
+		return (ENODEV);
 	case DVD_STRUCT_LIST:
 		/*
 		 * This is the maximum allocation length for the READ DVD
@@ -4067,9 +4036,7 @@
 		length = 65535;
 		break;
 	default:
-		error = EINVAL;
-		goto bailout;
-		break; /* NOTREACHED */
+		return (EINVAL);
 	}
 
 	if (length != 0) {
@@ -4077,6 +4044,9 @@
 	} else
 		databuf = NULL;
 
+	cam_periph_lock(periph);
+	ccb = cdgetccb(periph, CAM_PRIORITY_NORMAL);
+
 	scsi_read_dvd_structure(&ccb->csio,
 				/* retries */ 1,
 				/* cbfcnp */ cddone,
@@ -4166,11 +4136,12 @@
 	}
 bailout:
 
+	xpt_release_ccb(ccb);
+	cam_periph_unlock(periph);
+
 	if (databuf != NULL)
 		free(databuf, M_DEVBUF);
 
-	xpt_release_ccb(ccb);
-
 	return(error);
 }