From c9899b89b05e775e9fdd2846986566030fe73838 Mon Sep 17 00:00:00 2001 From: Jin Qian Date: Tue, 28 Feb 2017 15:09:42 -0800 Subject: [PATCH] ANDROID: uid_sys_stats: fix negative write bytes. A task can cancel writes made by other tasks. In rare cases, cancelled_write_bytes is larger than write_bytes if the task itself didn't make any write. This doesn't affect total size but may cause confusion when looking at IO usage on individual tasks. Bug: 35851986 Change-Id: If6cb549aeef9e248e18d804293401bb2b91918ca Signed-off-by: Jin Qian Signed-off-by: Francisco Franco --- drivers/misc/uid_sys_stats.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/drivers/misc/uid_sys_stats.c b/drivers/misc/uid_sys_stats.c index 0b26866617a..21b6c112697 100644 --- a/drivers/misc/uid_sys_stats.c +++ b/drivers/misc/uid_sys_stats.c @@ -211,14 +211,21 @@ static const struct file_operations uid_remove_fops = { .write = uid_remove_write, }; +static u64 compute_write_bytes(struct task_struct *task) +{ + if (task->ioac.write_bytes <= task->ioac.cancelled_write_bytes) + return 0; + + return task->ioac.write_bytes - task->ioac.cancelled_write_bytes; +} + static void add_uid_io_curr_stats(struct uid_entry *uid_entry, struct task_struct *task) { struct io_stats *io_curr = &uid_entry->io[UID_STATE_TOTAL_CURR]; io_curr->read_bytes += task->ioac.read_bytes; - io_curr->write_bytes += - task->ioac.write_bytes - task->ioac.cancelled_write_bytes; + io_curr->write_bytes += compute_write_bytes(task); io_curr->rchar += task->ioac.rchar; io_curr->wchar += task->ioac.wchar; } @@ -229,8 +236,7 @@ static void clean_uid_io_last_stats(struct uid_entry *uid_entry, struct io_stats *io_last = &uid_entry->io[UID_STATE_TOTAL_LAST]; io_last->read_bytes -= task->ioac.read_bytes; - io_last->write_bytes -= - task->ioac.write_bytes - task->ioac.cancelled_write_bytes; + io_last->write_bytes -= compute_write_bytes(task); io_last->rchar -= task->ioac.rchar; io_last->wchar -= task->ioac.wchar; } -- 2.20.1