From 7d46883724e04494a4a2df539655fecfd546e827 Mon Sep 17 00:00:00 2001 From: Martin Fuzzey Date: Fri, 10 Jan 2020 16:44:01 +0100 Subject: [PATCH] binder: fix log spam for existing debugfs file creation. commit eb143f8756e77c8fcfc4d574922ae9efd3a43ca9 upstream. Since commit 43e23b6c0b01 ("debugfs: log errors when something goes wrong") debugfs logs attempts to create existing files. However binder attempts to create multiple debugfs files with the same name when a single PID has multiple contexts, this leads to log spamming during an Android boot (17 such messages during boot on my system). Fix this by checking if we already know the PID and only create the debugfs entry for the first context per PID. Do the same thing for binderfs for symmetry. Signed-off-by: Martin Fuzzey Acked-by: Todd Kjos Fixes: 43e23b6c0b01 ("debugfs: log errors when something goes wrong") Cc: stable Link: https://lore.kernel.org/r/1578671054-5982-1-git-send-email-martin.fuzzey@flowbird.group Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 37 +++++++++++++++++++------------------ 1 file changed, 19 insertions(+), 18 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 976a694..254f87b 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -5203,10 +5203,11 @@ err_bad_arg: static int binder_open(struct inode *nodp, struct file *filp) { - struct binder_proc *proc; + struct binder_proc *proc, *itr; struct binder_device *binder_dev; struct binderfs_info *info; struct dentry *binder_binderfs_dir_entry_proc = NULL; + bool existing_pid = false; binder_debug(BINDER_DEBUG_OPEN_CLOSE, "%s: %d:%d\n", __func__, current->group_leader->pid, current->pid); @@ -5239,19 +5240,24 @@ static int binder_open(struct inode *nodp, struct file *filp) filp->private_data = proc; mutex_lock(&binder_procs_lock); + hlist_for_each_entry(itr, &binder_procs, proc_node) { + if (itr->pid == proc->pid) { + existing_pid = true; + break; + } + } hlist_add_head(&proc->proc_node, &binder_procs); mutex_unlock(&binder_procs_lock); - if (binder_debugfs_dir_entry_proc) { + if (binder_debugfs_dir_entry_proc && !existing_pid) { char strbuf[11]; snprintf(strbuf, sizeof(strbuf), "%u", proc->pid); /* - * proc debug entries are shared between contexts, so - * this will fail if the process tries to open the driver - * again with a different context. The priting code will - * anyway print all contexts that a given PID has, so this - * is not a problem. + * proc debug entries are shared between contexts. + * Only create for the first PID to avoid debugfs log spamming + * The printing code will anyway print all contexts for a given + * PID so this is not a problem. */ proc->debugfs_entry = debugfs_create_file(strbuf, 0444, binder_debugfs_dir_entry_proc, @@ -5259,19 +5265,16 @@ static int binder_open(struct inode *nodp, struct file *filp) &proc_fops); } - if (binder_binderfs_dir_entry_proc) { + if (binder_binderfs_dir_entry_proc && !existing_pid) { char strbuf[11]; struct dentry *binderfs_entry; snprintf(strbuf, sizeof(strbuf), "%u", proc->pid); /* * Similar to debugfs, the process specific log file is shared - * between contexts. If the file has already been created for a - * process, the following binderfs_create_file() call will - * fail with error code EEXIST if another context of the same - * process invoked binder_open(). This is ok since same as - * debugfs, the log file will contain information on all - * contexts of a given PID. + * between contexts. Only create for the first PID. + * This is ok since same as debugfs, the log file will contain + * information on all contexts of a given PID. */ binderfs_entry = binderfs_create_file(binder_binderfs_dir_entry_proc, strbuf, &proc_fops, (void *)(unsigned long)proc->pid); @@ -5281,10 +5284,8 @@ static int binder_open(struct inode *nodp, struct file *filp) int error; error = PTR_ERR(binderfs_entry); - if (error != -EEXIST) { - pr_warn("Unable to create file %s in binderfs (error %d)\n", - strbuf, error); - } + pr_warn("Unable to create file %s in binderfs (error %d)\n", + strbuf, error); } } -- 2.7.4