On Wed, 18 Nov 2015, Brian Norris wrote: > On Wed, Nov 18, 2015 at 11:04:11PM +0100, Julia Lawall wrote: > > This patch addresses several related memory management issues in the probe > > function: > > > > 1. for_each_available_child_of_node performs an of_node_get on each > > iteration, so a break out of the loop requires an of_node_put. > > > > A simplified version of the semantic patch that fixes this problem is as > > follows (http://coccinelle.lip6.fr): > > > > // <smpl> > > @@ > > expression root,e; > > local idexpression child; > > @@ > > > > for_each_available_child_of_node(root, child) { > > ... when != of_node_put(child) > > when != e = child > > ( > > return child; > > | > > + of_node_put(child); > > ? return ...; > > ) > > ... > > } > > // </smpl> > > Good catch again > > > 2. The devm_kzalloc'd data is not used if brcmnand_init_cs fails. Free it > > immediately, using devm_kfree in this case, instead of waiting for the > > remove function. > > Same > > > 3. If the continue is not taken, then host is added to a list, that has a > > lifetime beyond the end of the for_each_available_child_of_node loop body. > > Thus, of_node_get is needed on child, which is referenced by host. A > > corresponding of_node_put is needed in the remove function. > > This one's a bit silly. We really shouldn't be keeping the reference in > 'host' at all. Also, as of commit 215a02fd3087 ("mtd: grab a reference to > the MTD of_node before registering it"), the MTD core will actually be > refcounting the node for us, too, so this isn't really necessary. > > I have a patch to remove brcmnand_host::of_node (appended below), which > should make this step obsolete, and be more obvious that no extra > of_node_get()'ing is required. OK. Should I resend my patch without this change? julia > > Signed-off-by: Julia Lawall <Julia.Lawall@xxxxxxx> > > > > --- > > > > One could consider whether the of_node_get should be on host->of_node, > > which looks more similar to the thing that is stored in the list. I used > > child, to be more similar to the of_node_put in the same function. > > > > drivers/mtd/nand/brcmnand/brcmnand.c | 14 ++++++++++---- > > 1 file changed, 10 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c > > index 2a437c7..b0cb55d 100644 > > --- a/drivers/mtd/nand/brcmnand/brcmnand.c > > +++ b/drivers/mtd/nand/brcmnand/brcmnand.c > > @@ -2237,16 +2237,20 @@ int brcmnand_probe(struct platform_device *pdev, struct brcmnand_soc *soc) > > struct brcmnand_host *host; > > > > host = devm_kzalloc(dev, sizeof(*host), GFP_KERNEL); > > - if (!host) > > + if (!host) { > > + of_node_put(child); > > return -ENOMEM; > > In code reading, I noticed that we don't actually cleanup for prior > iterations of brcmnand_init_cs() here. i.e., if we're exiting here, we > should be doing nand_release() on all previously-registered chips. > > > + } > > host->pdev = pdev; > > host->ctrl = ctrl; > > host->of_node = child; > > > > ret = brcmnand_init_cs(host); > > - if (ret) > > + if (ret) { > > + devm_kfree(dev, host); > > continue; /* Try all chip-selects */ > > - > > + } > > + of_node_get(child); > > list_add_tail(&host->node, &ctrl->host_list); > > } > > } > > @@ -2264,8 +2268,10 @@ int brcmnand_remove(struct platform_device *pdev) > > struct brcmnand_controller *ctrl = dev_get_drvdata(&pdev->dev); > > struct brcmnand_host *host; > > > > - list_for_each_entry(host, &ctrl->host_list, node) > > + list_for_each_entry(host, &ctrl->host_list, node) { > > + of_node_put(host->of_node); > > nand_release(&host->mtd); > > + } > > > > dev_set_drvdata(&pdev->dev, NULL); > > > > Patch to kill off some of this: > > ---8<--- > From 6c51a9ef1325e7b06a7623c1fbca1adf6eeb8253 Mon Sep 17 00:00:00 2001 > From: Brian Norris <computersforpeace@xxxxxxxxx> > Date: Wed, 18 Nov 2015 14:33:24 -0800 > Subject: [PATCH] mtd: brcmnand: drop brcmnand_host::of_node field > > We don't actually need to stash a copy of this device_node indefinitely; > we only need it in brcmnand_init_cs(). > > Signed-off-by: Brian Norris <computersforpeace@xxxxxxxxx> > Cc: <bcm-kernel-feedback-list@xxxxxxxxxxxx> > Cc: Kamal Dasu <kdasu.kdev@xxxxxxxxx> > --- > drivers/mtd/nand/brcmnand/brcmnand.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c > index c395b4a75fb1..351438a62aaa 100644 > --- a/drivers/mtd/nand/brcmnand/brcmnand.c > +++ b/drivers/mtd/nand/brcmnand/brcmnand.c > @@ -176,7 +176,6 @@ struct brcmnand_cfg { > > struct brcmnand_host { > struct list_head node; > - struct device_node *of_node; > > struct nand_chip chip; > struct mtd_info mtd; > @@ -1896,10 +1895,9 @@ static int brcmnand_setup_dev(struct brcmnand_host *host) > return 0; > } > > -static int brcmnand_init_cs(struct brcmnand_host *host) > +static int brcmnand_init_cs(struct brcmnand_host *host, struct device_node *dn) > { > struct brcmnand_controller *ctrl = host->ctrl; > - struct device_node *dn = host->of_node; > struct platform_device *pdev = host->pdev; > struct mtd_info *mtd; > struct nand_chip *chip; > @@ -2231,9 +2229,8 @@ int brcmnand_probe(struct platform_device *pdev, struct brcmnand_soc *soc) > return -ENOMEM; > host->pdev = pdev; > host->ctrl = ctrl; > - host->of_node = child; > > - ret = brcmnand_init_cs(host); > + ret = brcmnand_init_cs(host, child); > if (ret) > continue; /* Try all chip-selects */ > > -- > 2.6.0.rc2.230.g3dd15c0 > > -- > To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
